Fluorescence imaging with minimal area monolithic image sensor

ABSTRACT

Systems, methods, and devices for fluorescence imaging with a minimal area image sensor are disclosed. A system includes an emitter for emitting pulses of electromagnetic radiation and an image sensor comprising a pixel array for sensing reflected electromagnetic radiation, wherein the pixel array comprises active pixels and optical black pixels. The system includes a black clamp providing offset control for data generated by the pixel array and a controller comprising a processor in electrical communication with the image sensor and the emitter. The system is such that at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises one or more of: electromagnetic radiation having a wavelength from about 770 nm to about 790 nm; or electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/673,809, filed Nov. 4, 2019, and which claims the benefit of U.S. Provisional Patent Application No. 62/864,194, filed Jun. 20, 2019, titled “HYPERSPECTRAL AND FLUORESCENCE IMAGING WITH MINIMAL AREA MONOLITHIC IMAGE SENSOR,” which is incorporated herein by reference in its entirety, including but not limited to those portions that specifically appear hereinafter, the incorporation by reference being made with the following exception: In the event that any portion of the above-referenced provisional application is inconsistent with this application, this application supersedes the above-referenced provisional application.

TECHNICAL FIELD

This application is directed to digital imaging and is particularly directed to fluorescence imaging in a light deficient environment.

BACKGROUND

Advances in technology have provided advances in imaging capabilities for medical use. An endoscope may be used to look inside a body and examine the interior of an organ or cavity of the body. Endoscopes are used for investigating a patient's symptoms, confirming a diagnosis, or providing medical treatment. A medical endoscope may be used for viewing a variety of body systems and parts such as the gastrointestinal tract, the respiratory tract, the urinary tract, the abdominal cavity by way of a small incision, and so forth. Endoscopes may further be used for surgical procedures such as plastic surgery procedures, procedures performed on joints or bones, procedures performed on the neurological system, procedures performed within the abdominal cavity, and so forth.

In some instances of endoscopic imaging, it may be beneficial or necessary to view a space in color. A digital color image includes at least three layers, or “color channels,” that cumulatively form an image with a range of hues. Each of the color channels measures the intensity and chrominance of light for a spectral band. Commonly, a digital color image includes a color channel for red, green, and blue spectral bands of light (this may be referred to as a Red Green Blue or RGB image). Each of the red, green, and blue color channels include brightness information for the red, green, or blue spectral band of light. The brightness information for the separate red, green, and blue layers are combined to create the color image. Because a color image is made up of separate layers, a conventional digital camera image sensor includes a color filter array that permits red, green, and blue visible light wavelengths to hit selected pixel sensors. Each individual pixel sensor element is made sensitive to red, green, or blue wavelengths and will only return image data for that wavelength. The image data from the total array of pixel sensors is combined to generate the RGB image. The at least three distinct types of pixel sensors consume significant physical space such that the complete pixel array cannot fit in the small distal end of an endoscope.

Because a traditional image sensor cannot fit in the distal end of an endoscope, the image sensor is traditionally located in a handpiece unit of an endoscope that is held by an endoscope operator and is not placed within the body cavity. In such an endoscope, light is transmitted along the length of the endoscope from the handpiece unit to the distal end of the endoscope. This configuration has significant limitations. Endoscopes with this configuration are delicate and can be easily misaligned or damaged when bumped or impacted during regular use. This can significantly degrade the quality of the images and necessitate that the endoscope be frequently repaired or replaced.

The traditional endoscope with the image sensor placed in the handpiece unit is further limited to capturing only color images. However, in some implementations, it may be desirable to capture images with fluorescence image data in addition to color image data. Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Certain fluorescent materials “glow” or emit a distinct color that is visible to the human eye when the fluorescent material is subjected to ultraviolet light or other wavelengths of electromagnetic radiation. Certain fluorescent materials will cease to glow nearly immediately when the radiation source stops.

Fluorescence occurs when an orbital electron of a molecule, atom, or nanostructure is excited by light or other electromagnetic radiation, and then relaxes to its ground state by emitting a photon from the excited state. The specific frequencies of electromagnetic radiation that excite the orbital electron, or are emitted by the photon during relaxation, are dependent on the atom, molecule, or nanostructure. Fluorescence imaging has numerous practical applications, including mineralogy, gemology, medicine, spectroscopy for chemical sensors, detecting biological processes or signals, and others. Fluorescence can be used in biochemistry and medicine as a non-destructive means for tracking or analyzing biological molecules. Some fluorescent reagents or dyes can be configured to attach to certain types of tissue and thereby draw attention to that type of tissue.

However, fluorescence imaging requires specialized emissions of electromagnetic radiation and specialized imaging sensors capable of reading the specific relaxation wavelength for a specific fluorescent reagent. Different reagents or dyes are sensitive to different wavelengths of electromagnetic radiation and emit different wavelengths of electromagnetic radiation when fluoresced. A fluorescent imaging system may be highly specialized and tuned for a certain reagent or dye. Such imaging systems are useful for limited applications and are not capable of fluorescing more than one reagent or structure during a single imaging session. It is very costly to use multiple distinct imaging systems that are each configured for fluorescing a different reagent. Additionally, it may be desirable to administer multiple fluorescent reagents in a single imaging session and view the multiple reagents in a single overlaid image.

In light of the foregoing, described herein are systems, methods, and devices for fluorescent imaging in a light deficient environment. Such systems, methods, and devices may provide multiple datasets for identifying critical structures in a body and providing precise and valuable information about the body cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive implementations of the disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Advantages of the disclosure will become better understood with regard to the following description and accompanying drawings where:

FIG. 1 is a schematic view of a system for digital imaging in a light deficient environment with a paired emitter and pixel array;

FIG. 2 is a system for providing illumination to a light deficient environment for endoscopic imaging;

FIG. 2A is a schematic diagram of complementary system hardware;

FIGS. 3A to 3D are illustrations of the operational cycles of a sensor used to construct an exposure frame;

FIG. 4A is a graphical representation of the operation of an embodiment of an electromagnetic emitter;

FIG. 4B is a graphical representation of varying the duration and magnitude of the emitted electromagnetic pulse to provide exposure control;

FIG. 5 is a graphical representation of an embodiment of the disclosure combining the operational cycles of a sensor, the electromagnetic emitter, and the emitted electromagnetic pulses of FIGS. 3A-4B, which demonstrate the imaging system during operation;

FIG. 6A is a schematic diagram of a process for recording a video with full spectrum light over a period of time from t(0) to t(1);

FIG. 6B is a schematic diagram of a process for recording a video by pulsing portioned spectrum light over a period of time from t(0) to t(1);

FIGS. 7A-7E illustrate schematic views of the processes over an interval of time for recording a frame of video for both full spectrum light and partitioned spectrum light;

FIG. 8A illustrates a traditional image sensor with optical black pixels disposed around a recording area of active pixels;

FIG. 8B illustrates an embodiment of a minimal area image sensor;

FIG. 9 is a readout sequence of an embodiment of a minimal area image sensor;

FIG. 10 is a readout sequence of an embodiment of a minimal area image sensor;

FIG. 11 is a circuit diagram of a black clamp circuit for sampling and adjusting for a dark signal captured by an image sensor;

FIG. 12 is a circuit diagram of a black clamp circuit wherein optical black clamp logic and sensor correction algorithms are moved off an image sensor;

FIG. 13 illustrates internal timing of an embodiment of a minimal area image sensor;

FIG. 14 is a schematic diagram of a process flow for a conventional on-chip imaging system for processing optical black clamp logic;

FIGS. 15A-15B are schematic diagrams of a process flow for calibrating a black clamp within a black clamp circuit and for calibrating line noise in a minimal area image sensor;

FIG. 16 is a schematic block diagram of an embodiment of a minimal area image sensor for endoscopic imaging applications in which an image sensor is incorporated in a distal end of an endoscope unit;

FIG. 17 is a circuit diagram of a minimal area image sensor for endoscopic applications in which the image sensor is incorporated in a distal end of an endoscope unit;

FIG. 18 is a schematic diagram of a process flow for concurrently adjusting an electromagnetic emitter and an image sensor;

FIG. 19 is a schematic diagram of a process flow for adjusting image sensor sensitivity;

FIG. 20 is a schematic diagram of a process flow for concurrently adjusting an image signal processor and an emitter based on histograms for frame cycles;

FIG. 21 is a schematic diagram of a process flow for limiting adjustments to an image signal processor and/or an emitter based on desired output;

FIG. 22 is a schematic diagram of a process flow for increasing dynamic range of an image by cycling a sensor through a first intensity of emission and a second intensity of emission, and combining data from the first and second intensities of emission;

FIG. 23 is a schematic diagram of a process flow for increasing dynamic range of an image by cycling a sensor through multiple intensities of emission and combining data from each of the multiple intensities of emission;

FIG. 24 is a schematic diagram of a process flow for performing corrections and adjustments on digital image data;

FIG. 25 is a schematic diagram of system hardware for writing, storing, and reading data from a digital video data stream;

FIG. 26 is a schematic diagram of method and hardware schematics for use with a partitioned light system;

FIG. 27 is a schematic diagram of a pattern reconstruction process for generating an RGB image with fluorescence data overlaid thereon by pulsing partitioned spectrums of light;

FIGS. 28A-28B are schematic diagram of a timing example for deploying two different pixel sensitive is in a dual sensitivity pixel array;

FIGS. 29A-29C illustrate the use of a white light emission that is pulsed and/or synced with a corresponding color sensor;

FIGS. 30A-30C illustrate a light source having a plurality of emitters;

FIG. 31 illustrates a single optical fiber outputting via a diffuser at an output to illuminate a scene in a light deficient environment;

FIG. 32 illustrates a portion of the electromagnetic spectrum divided into a plurality of different sub-spectrums which may be emitted by emitters of a light source in accordance with the principles and teachings of the disclosure;

FIG. 33 is a schematic diagram illustrating a timing sequence for emission and readout for generating an image frame comprising a plurality of exposure frames resulting from differing partitions of pulsed light;

FIG. 34 illustrates an endoscopic imaging system having a single cut filter;

FIG. 35 illustrates an endoscopic imaging system having multiple cut filters;

FIGS. 36A and 36B illustrate an implementation having a plurality of pixel arrays for producing a three-dimensional image in accordance with the principles and teachings of the disclosure;

FIGS. 37A and 37B illustrate a perspective view and a side view, respectively, of an implementation of an imaging sensor built on a plurality of substrates, wherein a plurality of pixel columns forming the pixel array are located on the first substrate and a plurality of circuit columns are located on a second substrate and showing an electrical connection and communication between one column of pixels to its associated or corresponding column of circuitry; and

FIGS. 38A and 38B illustrate a perspective view and a side view, respectively, of an implementation of an imaging sensor having a plurality of pixel arrays for producing a three-dimensional image, wherein the plurality of pixel arrays and the image sensor are built on a plurality of substrates.

DETAILED DESCRIPTION

Disclosed herein are systems, methods, and devices for digital imaging that may be primarily suited to medical applications such as medical endoscopic imaging. An embodiment of the disclosure is an endoscopic system for fluorescence and color imaging.

The imaging systems disclosed herein place aggressive constraints on the size of the image sensor. This enables the image sensor to be placed in a distal end of an endoscope and thereby enables the corresponding benefits of improved optical simplicity and increased mechanical robustness for the endoscope. However, placing these aggressive constraints on the image sensor area results in fewer and/or smaller pixels and can degrade image quality. The imaging systems disclosed herein provide means for extending the dynamic range, sensor sensitivity, and spatial resolution of resultant images while still decreasing the overall size of the image sensor.

In an embodiment, a system includes an image sensor comprising a pixel array. In the embodiment, the overall size of the pixel array is reduced by removing the conventionally used rows of optical black pixels. Image sensors incorporate special purpose optical black pixels that are used for calibrating the image sensor. Conventional pixel arrays include numerous optical black rows and optical black columns. An embodiment of the disclosure uses only optical black columns, and not optical black rows, for calibrating the image sensor. In the embodiment, the optical black columns may be read multiple times when calibrating the image sensor such that the total number of optical black columns may also be reduced. This embodiment assists in reducing the overall size of the pixel array and further enables more pixels to be dedicated to “active” sensing that returns image data.

The systems, methods, and devices disclosed herein can generate color Red-Green-Blue (RGB) imaging with fluorescence imaging data overlaid thereon. The fluorescence imaging data can be analyzed to identify the location of critical tissue structures in a body such as cancerous tissue, nervous tissue, muscle tissue, blood vessels, and so forth. In an embodiment, an endoscopic imaging system pulses an excitation wavelength of light for fluorescing a reagent that has been administered to a patient. The reagent may be configured to adhere to a specific type of tissue such as cancerous tissue, nervous tissue, muscle tissue, blood vessels, and so forth. The endoscopic imaging system may identify the location of the reagent within the patient's body and may therefore “see through” other tissues to identify the specific type of tissue to which the reagent has attached. By this method, the endoscopic imaging system disclosed herein can be leveraged to identify the specific location and boundaries of a cancerous tumor, the boundaries between different types of normal tissue, the direction of blood flow, and more.

Fluorescence imaging provides valuable information and may be used in the medical field for diagnostic imaging, providing visualization of a body cavity during medical procedures, and robotic procedures. Specialized reagents or dyes may be administered to a body to fluoresce certain tissues, structures, chemical processes, or biological processes. A fluorescent reagent may be configured to adhere to certain types of tissue, such as cancerous tissue, muscle tissue, diseased tissue, tissue undergoing a certain biological process, and so forth. The fluorescence of the reagent highlights the particular tissue to which it is attached. In an example, a fluorescent reagent is specialized to adhere to cancerous tissue and is used to highlight the location and boundaries of a cancerous tumor. Fluorescent reagents can be employed to highlight conditions or diseases such as cancerous cells, cells experiencing a certain biological or chemical process that may be associated with a condition or disease, certain types of tissue, and so forth.

In an embodiment, an endoscope generates fluorescence imaging in a light deficient environment such as a body cavity. The fluorescence imaging can be overlaid on an RGB video stream and used in real-time by a medical practitioner or computer program to differentiate between different types of tissue such as cancerous and non-cancerous cells. The real time fluorescence imaging can be used as a nondestructive means for tracking and visualizing a condition in the body that would otherwise not be visible by the human eye or distinguishable in an RGB image.

Conventional endoscopes are designed such that the image sensor is placed at a proximal end of the device within a handpiece unit. This configuration requires that incident light travel the length of the endoscope by way of precisely coupled optical elements. The precise optical elements can easily be misaligned during regular use, and this can lead to image distortion or image loss. Embodiments of the disclosure place an image sensor within a distal end of the endoscope itself. This provides greater optical simplicity when compared with implementations known in the art. However, an acceptable solution to this approach is by no means trivial and introduces its own set of engineering challenges, not least of which that the image sensor must fit within a highly constrained area. Disclosed herein are systems, methods, and devices for digital imaging in a light deficient environment that employ minimal area image sensors and can be configured for fluorescence and color imaging.

In some instances, it is desirable to generate endoscopic imaging with multiple data types or multiple images overlaid on one another. For example, it may be desirable to generate a color (“RGB”) image that further includes fluorescence imaging data overlaid on the RGB image. An overlaid image of this nature may enable a medical practitioner or computer program to identify critical body structures based on the fluorescence imaging data. Historically, this would require the use of multiple sensor systems including an image sensor for color imaging and one or more additional image sensors for fluorescence imaging. In such systems, the multiple image sensors would have multiple types of pixel sensors that are each sensitive to distinct ranges of electromagnetic radiation. In systems known in the art, this includes the three separate types of pixel sensors for generating an RGB color image along with additional pixel sensors for generating the fluorescence image data at different wavelengths of the electromagnetic spectrum. These multiple different pixel sensors consume a prohibitively large physical space and cannot be located at a distal tip of the endoscope. In systems known in the art, the camera or cameras are not placed at the distal tip of the endoscope and are instead placed in an endoscope handpiece or robotic unit. This introduces numerous disadvantages and causes the endoscope to be very delicate. The delicate endoscope may be damaged and image quality may be degraded when the endoscope is bumped or impacted during use. Considering the foregoing, disclosed herein are systems, methods, and devices for endoscopic imaging in a light deficient environment. The systems, methods, and devices disclosed herein provide means for employing multiple imaging techniques in a single imaging session while permitting one or more image sensors to be disposed in a distal tip of the endoscope.

Fluorescence Imaging

The systems, methods, and devices disclosed herein provide means for generating fluorescence imaging data in a light deficient environment. The fluorescence imaging data may be used to identify certain materials, tissues, components, or processes within a body cavity or other light deficient environment. In certain embodiments, fluorescence imaging is provided to a medical practitioner or computer-implemented program to enable the identification of certain structures or tissues within a body. Such fluorescence imaging data may be overlaid on black-and-white or RGB images to provide additional information and context.

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Certain fluorescent materials may “glow” or emit a distinct color that is visible to the human eye when the fluorescent material is subjected to ultraviolet light or other wavelengths of electromagnetic radiation. Certain fluorescent materials will cease to glow nearly immediately when the radiation source stops.

Fluorescence occurs when an orbital electron of a molecule, atom, or nanostructure is excited by light or other electromagnetic radiation, and then relaxes to its ground state by emitting a photon from the excited state. The specific frequencies of electromagnetic radiation that excite the orbital electron, or are emitted by the photon during relaxation, are dependent on the particular atom, molecule, or nanostructure. In most cases, the light emitted by the substance has a longer wavelength, and therefore lower energy, than the radiation that was absorbed by the substance. However, when the absorbed electromagnetic radiation is intense, it is possible for one electron to absorb two photons. This two-photon absorption can lead to emission of radiation having a shorter wavelength, and therefore higher energy, than the absorbed radiation. Additionally, the emitted radiation may also be the same wavelength as the absorbed radiation.

Fluorescence imaging has numerous practical applications, including mineralogy, gemology, medicine, spectroscopy for chemical sensors, detecting biological processes or signals, and so forth. Fluorescence may particularly be used in biochemistry and medicine as a non-destructive means for tracking or analyzing biological molecules. The biological molecules, including certain tissues or structures, may be tracked by analyzing the fluorescent emission of the biological molecules after being excited by a certain wavelength of electromagnetic radiation. However, relatively few cellular components are naturally fluorescent. In certain implementations, it may be desirable to visualize a certain tissue, structure, chemical process, or biological process that is not intrinsically fluorescent. In such an implementation, the body may be administered a dye or reagent that may include a molecule, protein, or quantum dot having fluorescent properties. The reagent or dye may then fluoresce after being excited by a certain wavelength of electromagnetic radiation. Different reagents or dyes may include different molecules, proteins, and/or quantum dots that will fluoresce at particular wavelengths of electromagnetic radiation. Thus, it may be necessary to excite the reagent or dye with a specialized band of electromagnetic radiation to achieve fluorescence and identify the desired tissue, structure, or process in the body.

Fluorescence imaging may provide valuable information in the medical field that may be used for diagnostic purposes and/or may be visualized in real-time during a medical procedure. Specialized reagents or dyes may be administered to a body to fluoresce certain tissues, structures, chemical processes, or biological processes. The fluorescence of the reagent or dye may highlight body structures such as blood vessels, nerves, particular organs, and so forth. Additionally, the fluorescence of the reagent or dye may highlight conditions or diseases such as cancerous cells or cells experiencing a certain biological or chemical process that may be associated with a condition or disease. The fluorescence imaging may be used in real-time by a medical practitioner or computer program for differentiating between, for example, cancerous and non-cancerous cells during a surgical tumor extraction. The fluorescence imaging may further be used as a non-destructive means for tracking and visualizing over time a condition in the body that would otherwise not be visible by the human eye or distinguishable in an RGB image.

The systems, methods, and devices for generating fluorescence imaging data may be used in coordination with reagents or dyes. Some reagents or dyes are known to attach to certain types of tissues and fluoresce at specific wavelengths of the electromagnetic spectrum. In an implementation, a reagent or dye is administered to a patient that is configured to fluoresce when activated by certain wavelengths of light. The endoscopic imaging system disclosed herein is used to excite and fluoresce the reagent or dye. The fluorescence of the reagent or dye is captured by the endoscopic imaging system to aid in the identification of tissues or structures in the body cavity. In an implementation, a patient is administered a plurality of reagents or dyes that are each configured to fluoresce at different wavelengths and/or provide an indication of different structures, tissues, chemical reactions, biological processes, and so forth. In such an implementation, the endoscopic imaging system emits each of the applicable wavelengths to fluoresce each of the applicable reagents or dyes. This may negate the need to perform individual imaging procedures for each of the plurality of reagents or dyes.

Imaging reagents can enhance imaging capabilities in pharmaceutical, medical, biotechnology, diagnostic, and medical procedure industries. Many imaging techniques such as X-ray, computer tomography (CT), ultrasound, magnetic resonance imaging (MRI), and nuclear medicine, mainly analyze anatomy and morphology and are unable to detect changes at the molecular level. Fluorescent reagents, dyes, and probes, including quantum dot nanoparticles and fluorescent proteins, assist medical imaging technologies by providing additional information about certain tissues, structures, chemical processes, and/or biological processes that are present within the imaging region. Imaging using fluorescent reagents enables cell tracking and/or the tracking of certain molecular biomarkers. Fluorescent reagents may be applied for imaging cancer, infection, inflammation, stem cell biology, and others. Numerous fluorescent reagents and dyes are being developed and applied for visualizing and tracking biological processes in a non-destructive manner. Such fluorescent reagents may be excited by a certain wavelength or band of wavelengths of electromagnetic radiation. Similarly, those fluorescent reagents may emit relaxation energy at a certain wavelength or band of wavelengths when fluorescing, and the emitted relaxation energy may be read by a sensor to determine the location and/or boundaries of the reagent or dye.

In an embodiment of the disclosure, an endoscopic imaging system pulses electromagnetic radiation for exciting an electron in a fluorescent reagent or dye. The endoscopic imaging system may pulse multiple different wavelengths of electromagnetic radiation for fluorescing multiple different reagents or dyes during a single imaging session. The endoscope includes an image sensor that is sensitive to the relaxation wavelength(s) of the one or more reagents or dyes. The imaging data generated by the image sensor can be used to identify a location and boundary of the one or more reagents or dyes. The endoscope system may further pulse electromagnetic radiation in red, green, and blue bands of visible light such that the fluorescence imaging can be overlaid on an RGB video stream.

Pulsed Imaging

Some implementations of the disclosure include aspects of a combined sensor and system design that allows for high definition imaging with reduced pixel counts in a controlled illumination environment. This is accomplished with frame-by-frame pulsing of a single-color wavelength and switching or alternating each frame between a single, different color wavelength using a controlled light source in conjunction with high frame capture rates and a specially designed corresponding monochromatic sensor. The pixels may be color agnostic such that each pixel generates data for each pulse of electromagnetic radiation, including pulses for red, green, and blue visible light wavelengths along with other wavelengths used for fluorescence imaging.

For the purposes of promoting an understanding of the principles in accordance with the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the disclosure as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the disclosure claimed.

Before the structure, systems and methods for producing an image in a light deficient environment are disclosed and described, it is to be understood that this disclosure is not limited to the particular structures, configurations, process steps, and materials disclosed herein as such structures, configurations, process steps, and materials may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the disclosure will be limited only by the appended claims and equivalents thereof.

In describing and claiming the subject matter of the disclosure, the following terminology will be used in accordance with the definitions set out below.

It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps.

As used herein, the phrase “consisting of” and grammatical equivalents thereof exclude any element or step not specified in the claim.

As used herein, the phrase “consisting essentially of” and grammatical equivalents thereof limit the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic or characteristics of the claimed disclosure.

As used herein, the term “proximal” shall refer broadly to the concept of a portion nearest an origin.

As used herein, the term “distal” shall generally refer to the opposite of proximal, and thus to the concept of a portion farther from an origin, or a furthest portion, depending upon the context.

As used herein, color sensors or multi spectrum sensors are those sensors known to have a color filter array (CFA) thereon to filter the incoming electromagnetic radiation into its separate components. In the visual range of the electromagnetic spectrum, such a CFA may be built on a Bayer pattern or modification thereon to separate green, red and blue spectrum components of the light.

As used herein, monochromatic sensor refers to an unfiltered imaging sensor. Since the pixels are color agnostic, the effective spatial resolution is appreciably higher than for their color (typically Bayer-pattern filtered) counterparts in conventional single-sensor cameras. Monochromatic sensors may also have higher quantum efficiency because fewer incident photons are wasted between individual pixels.

As used herein, an emitter is a device that is capable of generating and emitting electromagnetic pulses. Various embodiments of emitters may be configured to emit pulses and have very specific frequencies or ranges of frequencies from within the entire electromagnetic spectrum. Pulses may comprise wavelengths from the visible and non-visible ranges. An emitter may be cycled on and off to produce a pulse or may produce a pulse with a shutter mechanism. An emitter may have variable power output levels or may be controlled with a secondary device such as an aperture or filter. An emitter may emit broad spectrum or full spectrum electromagnetic radiation that may produce pulses through color filtering or shuttering. An emitter may comprise a plurality of electromagnetic sources that act individually or in concert.

It should be noted that as used herein the term “light” is both a particle and a wavelength and is intended to denote electromagnetic radiation that is detectable by a pixel array 122 and may include wavelengths from the visible and non-visible spectrums of electromagnetic radiation. The term “partition” is used herein to mean a pre-determined range of wavelengths of the electromagnetic spectrum that is less than the entire spectrum, or in other words, wavelengths that make up some portion of the electromagnetic spectrum. As used herein, an emitter is a light source that may be controllable as to the portion of the electromagnetic spectrum that is emitted or that may operate as to the physics of its components, the intensity of the emissions, or the duration of the emission, or all the above. An emitter may emit light in any dithered, diffused, or collimated emission and may be controlled digitally or through analog methods or systems. As used herein, an electromagnetic emitter is a source of a burst of electromagnetic energy and includes light sources, such as lasers, LEDs, incandescent light, or any light source that can be digitally controlled.

Referring now to the figures, FIG. 1 illustrates a schematic diagram of a system 100 for sequential pulsed imaging in a light deficient environment. The system 100 can be deployed to generate an RGB image with fluorescence imaging data overlaid on the RGB image. The system 100 includes an emitter 102 and a pixel array 122. The emitter 102 pulses a partition of electromagnetic radiation in the light deficient environment 112 and the pixel array 122 senses instances of reflected electromagnetic radiation. The emitter 102 and the pixel array 122 work in sequence such that one or more pulses of a partition of electromagnetic radiation results in image data sensed by the pixel array 122.

It should be noted that as used herein the term “light” is both a particle and a wavelength and is intended to denote electromagnetic radiation that is detectable by a pixel array 122 and may include wavelengths from the visible and non-visible spectrums of electromagnetic radiation. The term “partition” is used herein to mean a pre-determined range of wavelengths of the electromagnetic spectrum that is less than the entire spectrum, or in other words, wavelengths that make up some portion of the electromagnetic spectrum. As used herein, an emitter is a light source that may be controllable as to the portion of the electromagnetic spectrum that is emitted or that may operate as to the physics of its components, the intensity of the emissions, or the duration of the emission, or all the above. An emitter may emit light in any dithered, diffused, or collimated emission and may be controlled digitally or through analog methods or systems. As used herein, an electromagnetic emitter is a source of a burst of electromagnetic energy and includes light sources, such as lasers, LEDs, incandescent light, or any light source that can be digitally controlled.

A pixel array 122 of an image sensor may be paired with the emitter 102 electronically, such that the emitter 102 and the pixel array 122 are synced during operation for both receiving the emissions and for the adjustments made within the system. The emitter 102 may be tuned to emit electromagnetic radiation in the form of a laser, which may be pulsed to illuminate a light deficient environment 112. The emitter 102 may pulse at an interval that corresponds to the operation and functionality of the pixel array 122. The emitter 102 may pulse light in a plurality of electromagnetic partitions such that the pixel array receives electromagnetic energy and produces a dataset that corresponds in time with each specific electromagnetic partition. For example, FIG. 1 illustrates an implementation wherein the emitter 102 emits four different partitions of electromagnetic radiation, including red 104, green 106, blue 108, and a fluorescence excitation 110 wavelength. The fluorescence excitation 110 wavelength may include a plurality of different partitions of electromagnetic radiation that are selected to fluoresce a plurality of fluorescent reagents that are present within the light deficient environment 112. The fluorescent excitation 110 wavelength may be selected to fluoresce a particular fluorescent reagent that is present in the light deficient environment 112.

The light deficient environment 112 includes structures, tissues, and other elements that reflect a combination of red 114, green 116, and/or blue 118 light. A structure that is perceived as being red 114 will reflect back pulsed red 104 light. The reflection off the red structure results in sensed red 105 by the pixel array 122 following the pulsed red 104 emission. The data sensed by the pixel array 122 results in a red exposure frame. A structure that is perceived as being green 116 will reflect back pulsed green 106 light. The reflection off the green structure results in sensed green 107 by the pixel array 122 following the pulsed green 106 emission. The data sensed by the pixel array 122 results in a green exposure frame. A structure that is perceived as being blue 118 will reflect back pulsed blue 108 light. The reflection off the blue structure results in sensed blue 109 by the pixel array 122 following the pulsed blue 108 emission. The data sensed by the pixel array 122 results in a blue exposure frame.

When a structure is a combination of colors, the structure will reflect back a combination of the pulsed red 104, pulsed green 106, and/or pulsed blue 108 emissions. For example, a structure that is perceived as being purple will reflect back light from the pulsed red 104 and pulsed blue 108 emissions. The resulting data sensed by the pixel array 122 will indicate that light was reflected in the same region following the pulsed red 104 and pulsed blue 108 emissions. When the resultant red exposure frame and blue exposure frames are combined to form the RGB image frame, the RGB image frame will indicate that the structure is purple.

In an embodiment where the light deficient environment 112 includes a fluorescent reagent or dye or includes one or more fluorescent structures, tissues, or other elements, the pulsing scheme may include the emission of a certain fluorescence excitation wavelength. The certain fluorescence excitation wavelength may be selected to fluoresce a known fluorescent reagent, dye, or other structure. The fluorescent structure will be sensitive to the fluorescence excitation wavelength and will emit a fluorescence relaxation wavelength. The fluorescence relaxation wavelength will be sensed by the pixel array 122 following the emission of the fluorescence excitation wavelength. The data sensed by the pixel array 122 results in a fluorescence exposure frame. The fluorescence exposure frame may be combined with multiple other exposure frames to form an image frame. The data in the fluorescence exposure frame may be overlaid on an RGB image frame that includes data from a red exposure frame, a green exposure frame, and a blue exposure frame.

In an embodiment where the light deficient environment 112 includes structures, tissues, or other materials that emit a spectral response to certain partitions of the electromagnetic spectrum, the pulsing scheme may include the emission of a hyperspectral partition of electromagnetic radiation for the purpose of eliciting the spectral response from the structures, tissues, or other materials present in the light deficient environment 112. The spectral response includes the emission or reflection of certain wavelengths of electromagnetic radiation. The spectral response can be sensed by the pixel array 122 and result in a hyperspectral exposure frame. The hyperspectral exposure frame may be combined with multiple other exposure frames to form an image frame. The data in the hyperspectral exposure frame may be overlaid on an RGB image frame that includes data from a red exposure frame, a green exposure frame, and a blue exposure frame.

In an embodiment, the pulsing scheme includes the emission of a laser mapping or tool tracking pattern. The reflected electromagnetic radiation sensed by the pixel array 122 following the emission of the laser mapping or tool tracking pattern results in a laser mapping exposure frame. The data in the laser mapping exposure frame may be provided to a corresponding system to identify, for example, distances between tools present in the light deficient environment 112, a three-dimensional surface topology of a scene in the light deficient environment 112, distances, dimensions, or positions of structures or objects within the scene, and so forth. This data may be overlaid on an RGB image frame or otherwise provided to a user of the system.

The emitter 102 may be a laser emitter that is capable of emitting pulsed red 104 light for generating sensed red 105 data for identifying red 114 elements within the light deficient environment 112. The emitter 102 is further capable of emitting pulsed green 106 light for generating sensed green 107 data for identifying green 116 elements within the light deficient environment. The emitter 102 is further capable of emitting pulsed blue 108 light for generating sensed blue 109 data for identifying blue 118 elements within the light deficient environment. The emitter 102 is further capable of emitting pulsed fluorescence excitation 110 wavelength(s) of electromagnetic radiation for identifying a fluorescent reagent 120 within the light deficient environment 112. The fluorescent reagent 120 is identified by exciting the fluorescent reagent 120 with the pulsed fluorescence excitation 110 light and then sensing (by the pixel array 122) the fluorescence relaxation 111 wavelength for that particular fluorescent reagent 120. The emitter 102 is capable of emitting the pulsed red 104, pulsed green 106, pulsed blue 108, and pulsed fluorescence excitation 110 wavelengths in any desired sequence.

The pixel array 122 senses reflected electromagnetic radiation. Each of the sensed red 105, the sensed green 107, the sensed blue 109, and the sensed fluorescence relaxation 111 data can be referred to as an “exposure frame.” Each exposure frame is assigned a specific color or wavelength partition, wherein the assignment is based on the timing of the pulsed color or wavelength partition from the emitter 102. The exposure frame in combination with the assigned specific color or wavelength partition may be referred to as a dataset. Even though the pixels 122 are not color-dedicated, they can be assigned a color for any given dataset based on a priori information about the emitter.

For example, during operation, after pulsed red 104 light is pulsed in the light deficient environment 112, the pixel array 122 senses reflected electromagnetic radiation. The reflected electromagnetic radiation results in an exposure frame, and the exposure frame is catalogued as sensed red 105 data because it corresponds in time with the pulsed red 104 light. The exposure frame in combination with an indication that it corresponds in time with the pulsed red 104 light is the “dataset.” This is repeated for each partition of electromagnetic radiation emitted by the emitter 102. The data created by the pixel array 122 includes the sensed red 105 exposure frame identifying red 114 components in the light deficient environment and corresponding in time with the pulsed red 104 light. The data further includes the sensed green 107 exposure frame identifying green 116 components in the light deficient environment and corresponding in time with the pulsed green 106 light. The data further includes the sensed blue 109 exposure frame identifying blue 118 components in the light deficient environment and corresponding in time with the pulsed blue 108 light. The data further includes the sensed fluorescence relaxation 111 exposure frame identifying the fluorescent reagent 120 and corresponding in time with the pulsed fluorescence excitation 110 wavelength(s) of light.

In one embodiment, three datasets representing RED, GREEN and BLUE electromagnetic pulses are combined to form a single image frame. Thus, the information in a red exposure frame, a green exposure frame, and a blue exposure frame are combined to form a single RGB image frame. One or more additional datasets representing other wavelength partitions may be overlaid on the single RGB image frame. The one or more additional datasets may represent, for example, fluorescence imaging responsive to the pulsed excitation 110 wavelength between 770 nm and 790 nm and between 795 nm and 815 nm.

It will be appreciated that the disclosure is not limited to any particular color combination or any particular electromagnetic partition, and that any color combination or any electromagnetic partition may be used in place of RED, GREEN and BLUE, such as Cyan, Magenta and Yellow; Ultraviolet; infrared; any combination of the foregoing, or any other color combination, including all visible and non-visible wavelengths, without departing from the scope of the disclosure. In the figure, the light deficient environment 112 to be imaged includes red 114, green 116, and blue 118 portions, and further includes a fluorescent reagent 120. As illustrated in the figure, the reflected light from the electromagnetic pulses only contains the data for the portion of the object having the specific color that corresponds to the pulsed color partition. Those separate color (or color interval) datasets can then be used to reconstruct the image by combining the datasets at 126. The information in each of the multiple exposure frames (i.e., the multiple datasets) may be combined by a controller 124, a control unit, a camera control unit, the image sensor, an image signal processing pipeline, or some other computing resource that is configurable to process the multiple exposure frames and combine the datasets at 126. The datasets may be combined to generate the single image frame within the endoscope unit itself or offsite by some other processing resource.

FIG. 2 is a system 200 for providing illumination to a light deficient environment, such as for endoscopic imaging. The system 200 may be used in combination with any of the systems, methods, or devices disclosed herein. The system 200 includes an emitter 202, a controller 204, a jumper waveguide 206, a waveguide connector 208, a lumen waveguide 210, a lumen 212, and an image sensor 214 with accompanying optical components (such as a lens). The emitter 202 (may be generically referred to as a “light source”) generates light that travels through the jumper waveguide 206 and the lumen waveguide 210 to illuminate a scene at a distal end of the lumen 212. The emitter 202 may be used to emit any wavelength of electromagnetic energy including visible wavelengths, infrared, ultraviolet, hyperspectral, fluorescence excitation, or other wavelengths. The lumen 212 may be inserted into a patient's body for imaging, such as during a procedure or examination. The light is output as illustrated by dashed lines 216. A scene illuminated by the light may be captured using the image sensor 214 and displayed for a doctor or some other medical personnel. The controller 204 may provide control signals to the emitter 202 to control when illumination is provided to a scene. In one embodiment, the emitter 202 and controller 204 are located within a camera control unit (CCU) or external console to which an endoscope is connected. If the image sensor 214 includes a CMOS sensor, light may be periodically provided to the scene in a series of illumination pulses between readout periods of the image sensor 214 during what is known as a blanking period. Thus, the light may be pulsed in a controlled manner to avoid overlapping into readout periods of the image pixels in a pixel array of the image sensor 214.

In one embodiment, the lumen waveguide 210 includes one or more optical fibers. The optical fibers may be made of a low-cost material, such as plastic to allow for disposal of the lumen waveguide 210 and/or other portions of an endoscope. In one embodiment, the lumen waveguide 210 is a single glass fiber having a diameter of 500 microns. The jumper waveguide 206 may be permanently attached to the emitter 202. For example, a jumper waveguide 206 may receive light from an emitter within the emitter 202 and provide that light to the lumen waveguide 210 at the location of the connector 208. In one embodiment, the jumper waveguide 106 includes one or more glass fibers. The jumper waveguide may include any other type of waveguide for guiding light to the lumen waveguide 210. The connector 208 may selectively couple the jumper waveguide 206 to the lumen waveguide 210 and allow light within the jumper waveguide 206 to pass to the lumen waveguide 210. In one embodiment, the lumen waveguide 210 is directly coupled to a light source without any intervening jumper waveguide 206.

The image sensor 214 includes a pixel array. In an embodiment, the image sensor 214 includes two or more pixel arrays for generating a three-dimensional image. The image sensor 214 may constitute two more image sensors that each have an independent pixel array and can operate independent of one another. The pixel array of the image sensor 214 includes active pixels and optical black (“OB”) or optically blind pixels. The active pixels may be clear “color agnostic” pixels that are capable of sensing imaging data for any wavelength of electromagnetic radiation. The optical black pixels are read during a blanking period of the pixel array when the pixel array is “reset” or calibrated. In an embodiment, light is pulsed during the blanking period of the pixel array when the optical black pixels are being read. After the optical black pixels have been read, the active pixels are read during a readout period of the pixel array. The active pixels may be charged by the electromagnetic radiation that is pulsed during the blanking period such that the active pixels are ready to be read by the image sensor during the readout period of the pixel array.

FIG. 2A is a schematic diagram of complementary system hardware such as a special purpose or general-purpose computer. Implementations within the scope of the present disclosure may also include physical and other non-transitory computer readable media for carrying or storing computer executable instructions and/or data structures. Such computer readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer readable media that stores computer executable instructions are computer storage media (devices). Computer readable media that carry computer executable instructions are transmission media. Thus, by way of example, and not limitation, implementations of the disclosure can comprise at least two distinctly different kinds of computer readable media: computer storage media (devices) and transmission media.

Computer storage media (devices) includes RAM, ROM, EEPROM, CD-ROM, solid state drives (“SSDs”) (e.g., based on RAM), Flash memory, phase-change memory (“PCM”), other types of memory, other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

A “network” is defined as one or more data links that enable the transport of electronic data between computer systems and/or modules and/or other electronic devices. In an implementation, a sensor and camera control unit may be networked to communicate with each other, and other components, connected over the network to which they are connected. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and/or data links, which can be used to carry desired program code means in the form of computer executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above should also be included within the scope of computer readable media.

Further, upon reaching various computer system components, program code means in the form of computer executable instructions or data structures that can be transferred automatically from transmission media to computer storage media (devices) (or vice versa). For example, computer executable instructions or data structures received over a network or data link can be buffered in RAM within a network interface module (e.g., a “NIC”), and then eventually transferred to computer system RAM and/or to less volatile computer storage media (devices) at a computer system. RAM can also include solid state drives (SSDs or PCIx based real time memory tiered storage, such as FusionIO). Thus, it should be understood that computer storage media (devices) can be included in computer system components that also (or even primarily) utilize transmission media.

Computer executable instructions comprise, for example, instructions and data which, when executed by one or more processors, cause a general-purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

Those skilled in the art will appreciate that the disclosure may be practiced in network computing environments with many types of computer system configurations, including, personal computers, desktop computers, laptop computers, message processors, control units, camera control units, hand-held devices, hand pieces, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, tablets, pagers, routers, switches, various storage devices, and the like. It should be noted that any of the above-mentioned computing devices may be provided by or located within a brick and mortar location. The disclosure may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

Further, where appropriate, functions described herein can be performed in one or more of: hardware, software, firmware, digital components, or analog components. For example, one or more application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) can be programmed to carry out one or more of the systems and procedures described herein. Certain terms are used throughout the following description and Claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name, but not function.

FIG. 2A is a block diagram illustrating an example computing device 250. Computing device 250 may be used to perform various procedures, such as those discussed herein. Computing device 250 can function as a server, a client, or any other computing entity. Computing device 250 can perform various monitoring functions as discussed herein, and can execute one or more application programs, such as the application programs described herein. Computing device 250 can be any of a wide variety of computing devices, such as a desktop computer, a notebook computer, a server computer, a handheld computer, camera control unit, tablet computer and the like.

Computing device 250 includes one or more processor(s) 252, one or more memory device(s) 254, one or more interface(s) 256, one or more mass storage device(s) 258, one or more Input/Output (I/O) device(s) 260, and a display device 280 all of which are coupled to a bus 262. Processor(s) 252 include one or more processors or controllers that execute instructions stored in memory device(s) 254 and/or mass storage device(s) 258. Processor(s) 252 may also include various types of computer readable media, such as cache memory.

Memory device(s) 254 include various computer readable media, such as volatile memory (e.g., random access memory (RAM) 264) and/or nonvolatile memory (e.g., read-only memory (ROM) 266). Memory device(s) 254 may also include rewritable ROM, such as Flash memory.

Mass storage device(s) 258 include various computer readable media, such as magnetic tapes, magnetic disks, optical disks, solid-state memory (e.g., Flash memory), and so forth. As shown in FIG. 2, a particular mass storage device is a hard disk drive 274. Various drives may also be included in mass storage device(s) 258 to enable reading from and/or writing to the various computer readable media. Mass storage device(s) 258 include removable media 276 and/or non-removable media.

I/O device(s) 260 include various devices that allow data and/or other information to be input to or retrieved from computing device 250. Example I/O device(s) 260 include digital imaging devices, electromagnetic sensors and emitters, cursor control devices, keyboards, keypads, microphones, monitors or other display devices, speakers, printers, network interface cards, modems, lenses, CCDs or other image capture devices, and the like.

Display device 280 includes any type of device capable of displaying information to one or more users of computing device 250. Examples of display device 280 include a monitor, display terminal, video projection device, and the like.

Interface(s) 256 include various interfaces that allow computing device 250 to interact with other systems, devices, or computing environments. Example interface(s) 256 may include any number of different network interfaces 270, such as interfaces to local area networks (LANs), wide area networks (WANs), wireless networks, and the Internet. Other interface(s) include user interface 268 and peripheral device interface 272. The interface(s) 256 may also include one or more user interface elements 268. The interface(s) 256 may also include one or more peripheral interfaces such as interfaces for printers, pointing devices (mice, track pad, etc.), keyboards, and the like.

Bus 262 allows processor(s) 252, memory device(s) 254, interface(s) 256, mass storage device(s) 258, and I/O device(s) 260 to communicate with one another, as well as other devices or components coupled to bus 262. Bus 262 represents one or more of several types of bus structures, such as a system bus, PCI bus, IEEE 1394 bus, USB bus, and so forth.

For purposes of illustration, programs and other executable program components are shown herein as discrete blocks, although it is understood that such programs and components may reside at various times in different storage components of computing device 250 and are executed by processor(s) 252. Alternatively, the systems and procedures described herein can be implemented in hardware, or a combination of hardware, software, and/or firmware. For example, one or more application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) can be programmed to carry out one or more of the systems and procedures described herein.

FIG. 3A illustrates the operational cycles of a sensor used in rolling readout mode or during the sensor readout 300. The frame readout may start at and may be represented by vertical line 310. The read-out period is represented by the diagonal or slanted line 302. The active pixels of the pixel array of the image sensor may be read out on a row by row basis, the top of the downwards slanted edge being the sensor top row 312 and the bottom of the downwards slanted edge being the sensor bottom row 314. The time between the last row readout and the next readout cycle may be called the blanking period 316. It should be noted that some of the sensor pixel rows might be covered with a light shield (e.g., a metal coating or any other substantially black layer of another material type). These covered pixel rows may be referred to as optical black rows 318 and 320. Optical black rows 318 and 320 may be used as input for correction algorithms. As shown in FIG. 3A, these optical black rows 318 and 320 may be located on the top of the pixel array or at the bottom of the pixel array or at the top and the bottom of the pixel array.

FIG. 3B illustrates a process of controlling the amount of electromagnetic radiation, e.g., light, that is exposed to a pixel, thereby integrated or accumulated by the pixel. It will be appreciated that photons are elementary particles of electromagnetic radiation. Photons are integrated, absorbed, or accumulated by each pixel and converted into an electrical charge or current. An electronic shutter or rolling shutter (shown by dashed line 322) may be used to start the integration time by resetting the pixel. The light will then integrate until the next readout phase. The position of the electronic shutter 322 can be moved between two readout cycles 302 to control the pixel saturation for a given amount of light. It should be noted that this technique allows for a constant integration time between two different lines but introduces a delay when moving from top to bottom rows.

FIG. 3C illustrates the case where the electronic shutter 322 has been removed. In this configuration, the integration of the incoming light may start during readout 302 and may end at the next readout cycle 302, which also defines the start of the next integration.

FIG. 3D shows a configuration without an electronic shutter 322, but with a controlled and pulsed light 330 during the blanking period 316. This ensures that all rows see the same light issued from the same light pulse 330. In other words, each row will start its integration in a dark environment, which may be at the optical black back row 320 of read out frame (m) for a maximum light pulse width, and will then receive a light strobe and will end its integration in a dark environment, which may be at the optical black front row 318 of the next succeeding read out frame (m+1) for a maximum light pulse width. In the FIG. 3D example, the image generated from the light pulse will be solely available during frame (m+1) readout without any interference with frames (m) and (m+2). It should be noted that the condition to have a light pulse to be read out only in one frame and not interfere with neighboring frames is to have the given light pulse firing during the blanking period 316. Because the optical black rows 318, 320 are insensitive to light, the optical black back rows 320 time of frame (m) and the optical black front rows 318 time of frame (m+1) can be added to the blanking period 316 to determine the maximum range of the firing time of the light pulse 330.

As illustrated in the FIG. 3A, a sensor may be cycled many times to receive data for each pulsed color or wavelength (e.g., Red, Green, Blue, or other wavelength on the electromagnetic spectrum). Each cycle may be timed. In an embodiment, the cycles may be timed to operate within an interval of 16.67 ms. In another embodiment, the cycles may be timed to operate within an interval of 8.3 ms. It will be appreciated that other timing intervals are contemplated by the disclosure and are intended to fall within the scope of this disclosure.

FIG. 4A graphically illustrates the operation of an embodiment of an electromagnetic emitter. An emitter may be timed to correspond with the cycles of a sensor, such that electromagnetic radiation is emitted within the sensor operation cycle and/or during a portion of the sensor operation cycle. FIG. 4A illustrates Pulse 1 at 402, Pulse 2 at 404, and Pulse 3 at 406. In an embodiment, the emitter may pulse during the readout period 302 of the sensor operation cycle. In an embodiment, the emitter may pulse during the blanking portion 316 of the sensor operation cycle. In an embodiment, the emitter may pulse for a duration that is during portions of two or more sensor operational cycles. In an embodiment, the emitter may begin a pulse during the blanking portion 316, or during the optical black portion 320 of the readout period 302, and end the pulse during the readout period 302, or during the optical black portion 318 of the readout period 302 of the next succeeding cycle. It will be understood that any combination of the above is intended to fall within the scope of this disclosure as long as the pulse of the emitter and the cycle of the sensor correspond.

FIG. 4B graphically represents varying the duration and magnitude of the emitted electromagnetic pulse (e.g., Pulse 1 at 412, Pulse 2 at 414, and Pulse 3 at 416) to control exposure. An emitter having a fixed output magnitude may be pulsed during any of the cycles noted above in relation to FIGS. 3D and 4A for an interval to provide the needed electromagnetic energy to the pixel array. An emitter having a fixed output magnitude may be pulsed at a longer interval of time, thereby providing more electromagnetic energy to the pixels or the emitter may be pulsed at a shorter interval of time, thereby providing less electromagnetic energy. Whether a longer or shorter interval time is needed depends upon the operational conditions.

In contrast to adjusting the interval of time the emitter pulses a fixed output magnitude, the magnitude of the emission itself may be increased to provide more electromagnetic energy to the pixels. Similarly, decreasing the magnitude of the pulse provides less electromagnetic energy to the pixels. It should be noted that an embodiment of the system may have the ability to adjust both magnitude and duration concurrently, if desired. Additionally, the sensor may be adjusted to increase its sensitivity and duration as desired for optimal image quality. FIG. 4B illustrates varying the magnitude and duration of the pulses. In the illustration, Pulse 1 at 412 has a higher magnitude or intensity than either Pulse 2 at 414 or Pulse 3 at 416. Additionally, Pulse 1 at 412 has a shorter duration than Pulse 2 at 414 or Pulse 3 at 416, such that the electromagnetic energy provided by the pulse is illustrated by the area under the pulse shown in the illustration. In the illustration, Pulse 2 at 414 has a relatively low magnitude or intensity and a longer duration when compared to either Pulse 1 at 412 or Pulse 3 at 416. Finally, in the illustration, Pulse 3 at 416 has an intermediate magnitude or intensity and duration, when compared to Pulse 1 at 412 and Pulse 2 at 414.

FIG. 5 is a graphical representation of an embodiment of the disclosure combining the operational cycles, the electromagnetic emitter, and the emitted electromagnetic pulses of FIGS. 3A-3D and 4A to demonstrate the imaging system during operation in accordance with the principles and teachings of the disclosure. As can be seen in the figure, the electromagnetic emitter pulses the emissions primarily during the blanking period 316 of the image sensor such that the pixels will be charged and ready to read during the readout period 302 of the image sensor cycle. The dashed lines in FIG. 5 represent the pulses of electromagnetic radiation (from FIG. 4A). The pulses of electromagnetic radiation are primarily emitted during the blanking period 316 of the image sensor but may overlap with the readout period 302 of the image sensor.

An exposure frame includes the data read by the pixel array of the image sensor during a readout period 302. The exposure frame may be combined with an indication of what type of pulse was emitted by the emitter prior to the readout period 302. The combination of the exposure frame and the indication of the pulse type may be referred to as a dataset. Multiple exposure frames may be combined to generate a black-and-white or RGB color image. Additionally, hyperspectral, fluorescence, and/or laser mapping imaging data may be overlaid on a black-and-white or RGB image.

In an embodiment, an RGB image frame is generated based on three exposure frames, including a red exposure frame generated by the image sensor subsequent to a red emission, a green exposure frame generated by the image sensor subsequent to a green emission, and a blue exposure frame generated by the image sensor subsequent to a blue emission. Fluorescence imaging data may be overlaid on the RGB image frame. The fluorescence imaging data may be drawn from one or more fluorescence exposure frames. A fluorescence exposure frame includes data generated by the image sensor during the readout period 302 subsequent to emission of an excitation wavelength of electromagnetic radiation for exciting a fluorescent reagent. The data sensed by the pixel array subsequent to the excitation of the fluorescent reagent may be the relaxation wavelength emitted by the fluorescent reagent. The fluorescence exposure frame may include multiple fluorescence exposure frames that are each generated by the image sensor subsequent to a different type of fluorescence excitation emission. In an embodiment, the fluorescence exposure frame includes multiple fluorescence exposure frames, including a first fluorescence exposure frame generated by the image sensor subsequent to an emission of electromagnetic radiation with a wavelength from about 770 nm to about 790 and a second fluorescence exposure frame generated by the image sensor subsequent to an emission of electromagnetic radiation with a wavelength from about 795 nm to about 815 nm. The fluorescence exposure frame may include further additional fluorescence exposure frames that are generated by the image sensor subsequent to other fluorescence excitation emissions of light as needed based on the imaging application.

In an embodiment, an exposure frame is the data sensed by the pixel array during the readout period 302 that occurs subsequent to a blanking period 316. The emission of electromagnetic radiation is emitted during the blanking period 316. In an embodiment, a portion of the emission of electromagnetic radiation overlaps the readout period 316. The blanking period 316 occurs when optical black pixels of the pixel array are being read and the readout period 302 occurs when active pixels of the pixel array are being read. The blanking period 316 may overlap the readout period 302.

FIGS. 6A and 6B illustrate processes for recording an image frame. Multiple image frames may be strung together to generate a video stream. A single image frame may include data from multiple exposure frames, wherein an exposure frame is the data sensed by a pixel array subsequent to an emission of electromagnetic radiation. FIG. 6A illustrates a traditional process that is typically implemented with a color image sensor having a color filter array (CFA) for filtering out certain wavelengths of light per pixel. FIG. 6B is a process that is disclosed herein and can be implemented with a monochromatic “color agnostic” image sensor that is receptive to all wavelengths of electromagnetic radiation.

The process illustrated in FIG. 6A occurs from time t(0) to time t(1). The process begins with a white light emission 602 and sensing white light 604. The image is processed and displayed at 606 based on the sensing at 604.

The process illustrated in FIG. 6B occurs from time t(0) to time t(1). The process begins with an emission of green light 612 and sensing reflected electromagnetic radiation 614 subsequent to the emission of green light 612. The process continues with an emission of red light 616 and sensing reflected electromagnetic radiation 618 subsequent to the emission of red light 616. The process continues with an emission of blue light 620 and sensing reflected electromagnetic radiation 622 subsequent to the emission of blue light 620. The process continues with one or more emissions of a fluorescence excitation wavelengths 624 and sensing reflected electromagnetic energy 626 subsequent to each of the one or more emissions of fluorescence excitation wavelengths of electromagnetic radiation 624. The image is processed and displayed at 628 based on each of the sensed reflected electromagnetic energy instances 614, 618, 622, and 626.

The process illustrated in FIG. 6B provides a higher resolution image and provides a means for generating an RGB image that further includes fluorescence imaging data. When partitioned spectrums of light are used, (as in FIG. 6B) a sensor can be made sensitive to all wavelengths of electromagnetic energy. In the process illustrated in FIG. 6B, the monochromatic pixel array is instructed that it is sensing electromagnetic energy from a predetermined partition of the full spectrum of electromagnetic energy in each cycle. Therefore, to form an image the sensor need only be cycled with a plurality of differing partitions from within the full spectrum of light. The final image is assembled based on the multiple cycles. Because the image from each color partition frame cycle has a higher resolution (compared with a CFA pixel array), the resultant image created when the partitioned light frames are combined also has a higher resolution. In other words, because each and every pixel within the array (instead of, at most, every second pixel in a sensor with a CFA) is sensing the magnitudes of energy for a given pulse and a given scene, just fractions of time apart, a higher resolution image is created for each scene.

As can be seen graphically in the embodiments illustrated in FIGS. 6A and 6B between times t(0) and t(1), the sensor for the partitioned spectrum system in FIG. 6B has cycled at least four times for every one of the full spectrum system in FIG. 6A. In an embodiment, a display device (LCD panel) operates at 50-60 frames per second. In such an embodiment, the partitioned light system in FIG. 6B may operate at 200-240 frames per second to maintain the continuity and smoothness of the displayed video. In other embodiments, there may be different capture and display frame rates. Furthermore, the average capture rate could be any multiple of the display rate.

In an embodiment, it may be desired that not all partitions be represented equally within the system frame rate. In other words, not all light sources have to be pulsed with the same regularity so as to emphasize and de-emphasize aspects of the recorded scene as desired by the users. It should also be understood that non-visible and visible partitions of the electromagnetic spectrum may be pulsed together within a system with their respective data value being stitched into the video output as desired for display to a user.

An embodiment may comprise a pulse cycle pattern as follows:

i. Green pulse;

ii. Red pulse;

iii. Blue pulse;

iv. Green pulse;

v. Red pulse;

vi. Blue pulse;

vii. Fluorescence excitation pulse;

viii. (Repeat)

As can be seen in the example, a fluorescence excitation partition may be pulsed at a rate differing from the rates of the other partition pulses. This may be done to emphasize a certain aspect of the scene, with the fluorescence imaging data simply being overlaid with the other data in the video output to make the desired emphasis. It should be noted that the addition of a fluorescence partition on top of the RED, GREEN, and BLUE partitions does not necessarily require the serialized system to operate at four times the rate of a full spectrum non-serial system because every partition does not have to be represented equally in the pulse pattern. As seen in the embodiment, the addition of a partition pulse that is represented less in a pulse pattern (fluorescence excitation in the above example), would result in an increase of less than 20% of the cycling speed of the sensor to accommodate the irregular partition sampling.

In various embodiments, the pulse cycle pattern may further include any of the following wavelengths in any suitable order. Such wavelengths may be particularly suited for exciting a fluorescent reagent to generate fluorescence imaging data by sensing the relaxation emission of the fluorescent reagent based on a fluorescent reagent relaxation emission:

i. 770±20 nm;

ii. 770±10 nm;

iii. 770±5 nm;

iv. 790±20 nm;

v. 790±10 nm;

vi. 790±5 nm;

vii. 795±20 nm;

viii. 795±10 nm;

ix. 795±5 nm;

x. 815±20 nm;

xi. 815±10 nm;

xii. 815±5 nm;

xiii. 770 nm to 790 nm; and/or

xiv. 795 nm to 815 nm.

The partition cycles may be divided so as to accommodate or approximate various imaging and video standards. In an embodiment, the partition cycles may comprise pulses of electromagnetic energy in the Red, Green, and Blue spectrum as follows as illustrated best in FIGS. 7A-7D. In FIG. 7A, the different light intensities have been achieved by modulating the light pulse width or duration within the working range shown by the vertical grey dashed lines. In FIG. 7B, the different light intensities have been achieved by modulating the light power or the power of the electromagnetic emitter, which may be a laser or LED emitter, but keeping the pulse width or duration constant. FIG. 7C shows the case where both the light power and the light pulse width are being modulated, leading to greater flexibility. The partition cycles may use Cyan Magenta Yellow (CMY), infrared, ultraviolet, hyperspectral, and fluorescence using a non-visible pulse source mixed with visible pulse sources and any other color space required to produce an image or approximate a desired video standard that is currently known or yet to be developed. It should also be understood that a system may be able to switch between the color spaces on the fly to provide the desired image output quality.

In an embodiment using color spaces Green-Blue-Green-Red (as seen in FIG. 7D) it may be desirous to pulse the luminance components more often than the chrominance components because users are generally more sensitive to light magnitude differences than to light color differences. This principle can be exploited using a mono-chromatic sensor as illustrated in FIG. 7D. In FIG. 7D, green, which contains the most luminance information, may be pulsed more often or with more intensity in a (G-B-G-R-G-B-G-R . . . ) scheme to obtain the luminance data. Such a configuration would create a video stream that has perceptively more detail, without creating and transmitting unperceivable data.

In an embodiment, duplicating the pulse of a weaker partition may be used to produce an output that has been adjusted for the weaker pulse. For example, blue laser light is considered weak relative to the sensitivity of silicon-based pixels and is difficult to produce in comparison to the red or green light, and therefore may be pulsed more often during a frame cycle to compensate for the weakness of the light. These additional pulses may be done serially over time or by using multiple lasers that simultaneously pulse to produce the desired compensation effect. It should be noted that by pulsing during a blanking period (time during which the sensor is not reading out the pixel array), the sensor is insensitive to differences/mismatches between lasers of the same kind and simply accumulates the light for the desired output. In another embodiment, the maximum light pulse range may be different from frame to frame. This is shown in FIG. 7E, where the light pulses are different from frame to frame. The sensor may be built to be able to program different blanking times with a repeating pattern of two or three or four or n frames. In FIG. 7E, four different light pulses are illustrated, and Pulse 1 may repeat for example after Pulse 4 and may have a pattern of four frames with different blanking times. This technique can be used to place the most powerful partition on the smallest blanking time and therefore allow the weakest partition to have wider pulse on one of the next frames without the need of increasing the readout speed. The reconstructed frame can still have a regular pattern from frame to frame as it is constituted of many pulsed frames.

Referring now to FIGS. 8A and 8B, implementations of image sensors are illustrated. The image sensor illustrated in FIG. 8A is a traditional image sensor 800 common in the prior art. The minimal area image sensor 820 illustrated in FIG. 8B is a pixel array in accordance with the teachings and principles of the disclosure. The minimal area image sensor 820 may be used in a distal tip of an endoscope. The distal tip of an endoscope is necessarily small because the distal tip is usually inserted in small areas such as body cavities. The distal tip of an endoscope is often too small to accommodate a traditional image sensor 800.

Image sensors can incorporate special purpose, optically blind or optical black (“OB”) rows and/or columns. Optical black pixels may alternatively be referred to as manufacturing buffer pixels or dummy pixels. An optical black row 804 is located at the top and/or bottom of a record area 802. The record area 802 includes the imaging pixel array. An optical black column 806 is located to the right and/or left of the pixel array. The optical black rows and columns are used to offset calibration of the record area 802.

The example layout of the traditional image sensor 800 includes an optical black row 804 on the top and bottom of the traditional record area 802. The traditional image sensor 800 further includes an optical black column 806 on the left and right sides of the record area 802. The example layout of the minimal area image sensor 820 includes optical black columns 806 on the left and right sides of the record area 802. The minimal area image sensor 820 does not include any optical black rows 804. Each of the example embodiments may include a guard ring 808 surrounding the circumference of the image sensor 800, 820.

The optical black rows 804 may be used to monitor the analog pixel black level for purposes of an optical black clamp algorithm. The optical black rows 804 may also be used by a digital algorithm for the purpose of cancelling column fixed pattern noise (CFPN). The optical black columns 806 may be used to assess the line offset as a means to cancel out line noise in the record area 802. Because line noise can be temporal, the line offset may be computed anew for each line of the record area 802 in every frame.

The minimal area image sensor 820 provides an overall reduction in the size of the image sensor by removing the optical black rows 804 from the top and bottom sides of the record area 802. When deploying the minimal area image sensor 820, the optical black columns 806 are used for the optical black clamp algorithm rather than any optical black rows 804. In an embodiment, all fixed pattern noise, including column fixed pattern noise, can be cancelled by acquiring frames of dark data. This negates the need for a dedicated CFPN correction and its associated optical black rows 804.

The number of optical black columns 806 might typically be 100 or more depending on space constraints. The more optical black columns 806 that are available, the greater the line-offset precision may be. Greater precision means lower line noise post-correction. Normally, all available physical optical black pixels are read for each line as shown in FIG. 9. A further degree of pixel array size reduction can be achieved if, instead of having the requisite number of physical optical black pixels, (given a certain precision target), a smaller number of physical optical black pixels are implemented and the physical optical black pixels are resampled multiple times during the horizontal readout process of the record area 802 and the optical black columns 806. This approach is illustrated in FIG. 10.

In an alternative embodiment, a minimal area image sensor includes optical black rows 804 but does not include optical black columns 806. In such an embodiment, the optical black rows 804 may be read before and after reading the active pixels in the record area 802 of the pixel array.

FIG. 9 illustrates a readout sequence 908 for a pixel array. As shown in FIG. 9, the readout sequence 908 begins with column readout 906 for each of the optical black columns 904. The optical black columns 904 may be similar to those optical black columns 806 illustrated in FIGS. 8A and 8B. Upon completion of the column readout 906 for the optical black columns 904, the readout sequence 908 begins the column readout 906 for the record area 910. The record area 910 may be similar to the record area 802 illustrated in FIGS. 8A and 8B. The record area 910 may include clear pixels 902 or color agnostic pixels. The readout sequence 908 continues until the entire record area 910 has been read. After the record area 910 has been read, the optical black columns 904 on the opposite side are read. The readout sequence 908 continues line-by-line until every row of the pixel array has been read.

FIG. 10 illustrates a readout sequence 1008 for a pixel array having an area size reduction that reduces the number of optical black pixels. In the readout sequence 1008 illustrated in FIG. 10, the optical black columns 1004 undergo column readout 1006 multiple times. As shown in FIG. 10, the optical black column 1004 readout can be resampled m time or n times. The record area may include clear pixels 1002.

Raw CMOS image sensor data present at the output of the digitizer may be far from ideal. It may often be the case that the optimal order with which to read out a horizontal row of pixels does not equate to the actual physical order within the array. Also, raw data usually reveals undesirable artifacts that reflect the nature of the readout architecture. These readout artifacts may include column fixed pattern noise arising from the variation in offset from column to column and may further include temporal line noise resulting from circuit resets associated with the horizontal readout process.

Another property of CMOS (complementary metal oxide semiconductor) sensors is that a degree of dark signal may be generated by the photodiode within the pixel. The amount of integrated signal arising from dark signal depends on exposure time and temperature. Because the dark signal may be indistinguishable from photo-signal, changes in the dark signal translate to changes in signal pedestal in the analog domain. Therefore, it may be important to sample and adjust for the dark signal so the available dynamic range of the analog to digital converter can be fully exploited.

FIG. 11 illustrates a circuit diagram 1100 for sampling and adjusting for dark signal in a CMOS image sensor. The circuit diagram includes a black clamp 1102 for limiting or clamping output voltage from the image sensor. In an embodiment, the data from the optical black pixels of the pixel array of the image sensor are averaged in the on-chip logic of the image sensor and compared to a target digital black level. The black clamp 1102 performs continuous adjustments to an input offset voltage of the image sensor to bring the black level as close to the target as possible. These adjustments may be referred to as the black clamp algorithm 1112 or optical black clamp process.

As shown in FIG. 11, the black clamp 1102 process occurs before signals enter the pin grid array 1108 (PGA). The signal exits the pin grid array 1108 and is received by the analog to digital converter 1110 (ADC). The signal is processed by the black clamp algorithm at 1112. The signal is processed by the sensor correction algorithm at 1114. The signal is processed by the serializer at 1116. The digital to analog converter or charge pump connects at 1106 the black clamp 1102 with the black clamp algorithm 1112. In the embodiment illustrated in FIG. 11, the black clamp algorithm 1112 and the sensor correction algorithm 1114 are located on the image sensor such that those algorithms are processed on-sensor. The low-voltage differential signaling (LVDS) is a technical standard that specifies electrical characteristics of a differential, serial communications protocol.

The black clamp 1102 is an embodiment of a clamp circuit or clamper. The black clamp 1102 restricts or clamps the output voltage of the optical black pixels of the pixel array of the image sensor. In an embodiment, the clamping action performed by the black clamp 1102 is executed through the use of diodes. The black clamp 1102 may clamp the positive or negative peak excursions of the signal generated by the optical black pixels to a defined value by shifting its direct current value. In an embodiment, the black clamp 1102 does not restrict the peak-to-peak excursion of the optical black signals but shifts the entire signal up or down to place the peaks at a reference level. The black clamp 1102 may bind the upper or lower extreme of a waveform from the optical black pixels to a fixed direct current voltage level.

The majority of commercially available sensors incorporate processing logic on-chip to perform black clamp and digital noise corrections. In the case of endoscopic imaging where it may be desirable to use a minimal area image sensor, these corrections can be migrated to the image signal processing (ISP) chain. This improves overall system performance because the corrections are less resource limited when resident in a field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC) that has sufficient available logic gates and RAM (random access memory).

FIG. 12 is a circuit diagram 1200 for moving optical black clamp logic off of the image sensor along with sensor correction algorithms. In this case, information about the analog adjustments from the optical black clamp logic may be transmitted to the sensor by means of instructions via its command interface. As shown in FIG. 12, and especially when compared with the embodiment shown in FIG. 11, it can be seen that the black clamp algorithm and the sensor correction algorithm have been moved off the image sensor. The black clamp 1202 generates black clamp signals that are received by the pin grid array 1208. The signal processed by the pin grid array 1208 is received and processed by the analog to digital converter 1210. In contrast with the embodiment illustrated in FIG. 11, the signal is not processed by the black clamp algorithm or the sensor correction algorithm before the signal is serialized by the serializer 1212. A digital to analog converter or charge pump 1204 transmits the black clamp 1202 signal to a slow control 2-wire protocol 1206.

The adjustment of the black clamp level may be done by means of controlling a DC voltage (V_(blackclamp)) using a digital to analog converter (DAC) or charge pump on the sensor at 1204. Pixel voltage offsets entering the analog to digital converter move due to dark current in the photodiode. In some implementations, the digital to analog converter employed at step 1204 is regularly adjusted by assessing the black offset in the digital domain.

FIG. 13 illustrates the internal timing of an embodiment of a minimal area custom sensor. The timing may be implemented for the purpose of endoscopic imaging in the presence of controlled, pulsed illumination. Each frame period may comprise four distinct phases, which may be optimized for monochrome light pulsing and multiple pixel illuminations. During phases 1 and 3, data may be issued from the sensor which may be signal samples from physical pixels. These “service line” periods may be used for internal and external monitoring and for the encoding of certain types of non-pixel data within the line. Such internal monitoring may include the sensor temperature, voltages, and currents. Phase 2 is concerned with the sensor rolling readout including internal timing and synchronization. Phase 4 includes sensor configuration. During the configuration phase, the sensor output data lines may be reversed to accept incoming configuration commands. Therefore, the camera controller may be synchronized to the phase 4 period.

FIG. 14 illustrates a process flow 1400 for a conventional CMOS imaging system that processes optical black clamp logic on-chip. The process flow 1400 includes sampling at 1402 the next pixel and adding the next pixel to the accumulator. The process flow 1400 includes querying at 1404 whether it is the last pixel. If it is not the last pixel, the next pixel is sampled such that the step at 1402 is repeated. If it is the last pixel, then the process flow 1400 proceeds to computing at 1406 the black level and resets the accumulator. The process flow 1400 includes comparing at 1408 black level (B) to target (T) by way of the equation D=B−T. The process flow 1400 includes querying at 1410 whether the result of the equation (D) is greater than BigPush. If D is greater than BigPush, then large proportional adjustments are made to the black clamp voltage at 1412. If D is not greater than BigPush, the small incremental adjustments are made to the black clamp voltage at 1414. The process flow 1400 includes ignoring at 1416 the next N pixels where N is greater than the analog to digital converter latency.

There might typically be multiple samples and analog adjustments made per frame, from multiple optical black rows, while the optical black row pixels are present in the digital readout path. As discussed earlier, for a minimal area sensor, the number of optical black pixels should be reduced to the minimum necessary and this can be accomplished by eliminating the optical black rows and using the optical black columns to calibrate the black clamp as well as the line noise. The process flow 1500 in FIGS. 15A and 15B outlines a method of accomplishing this. The basic idea may be to accumulate the set of measured, uncorrected line offsets for the whole frame and use the final estimate to make the black clamp adjustment. Meanwhile, each individual line offset estimate may be fed to a later process to make a digital adjustment to the individual line.

The process flow 1500 includes sampling the next pixel at 1502 and querying whether the pixel is the first or second optical black pixel in the row at 1502. If the pixel is the first or second optical black pixel in the row, then the pixel is added at 1504 to the median first-in-first-out. Additionally, if the pixel is the first optical black pixel in the row, then the line offset accumulator is reset at 1504. The optical black value is stored at 1506 and then the next pixel is sampled at 1502. If the next pixel is not the first or second optical black pixel in a row as determined at 1502, then it is determined at 1508 whether the pixel is an optical black pixel. If the pixel is an optical black pixel, then the pixel is added at 1510 to the median first-in-first-out. The median is computed at 1512 and added to the line offset accumulator. If the pixel is not an optical black pixel as determined at 1508, then it is determined at 1514 whether the pixel is the first clear pixel. If the pixel is the first clear pixel, then the pixel is added at 1516 to the median first-in-first-out. If the pixel is not the first clear pixel as determined at 1514, then it is determined at 1518 whether the pixel is the second clear pixel. If the pixel is not the second clear pixel, then the next pixel is sampled at 1502. If the pixel is the second clear pixel as determined at 1518, then a second stored optical black is added at 1520 to the median first-in-first-out.

The process flow 1500 continues in FIG. 15B. The median is computed at 1522 and added to the line offset accumulator. The black offset is computed at 1524 for the row based on the line offset accumulator, port to line noise correction, and the pulse availability signal. The line offset is added at 1526 to the black level accumulator. At 1528 it is determined whether the row is the last row in the pixel array. If the row is not the last row in the pixel array as determined at 1528, then the process flow 1500 begins again by reading the next pixel at 1502. If the row is the last row as determined at 1528, then the black level estimate is computed at 1530 for the frame based on the line offset accumulator. Further, the line offset accumulator is reset at 1530. The black level (B) is compared to the target (T) at 1532 according to the equation D=B−T. At 1534, it is determined whether the result D is greater than BigPush. If the result D is greater than BigPush, then large proportional adjustments are made to the black clamp voltage at 1536. If the result D is not greater than BigPush, then small, incremental adjustments are made to the black clamp voltage at 1538.

FIG. 16 illustrates an overall block diagram for an embodiment of a minimal area sensor 1600 for endoscopic applications in which the sensor is incorporated into the distal end of the endoscope unit. The minimal area sensor 1600 includes an address decoder 1602 that receives signals from a two-wire slow control protocol. The address decoder 1602 sends signals to a command register 1604, a format register 1606, a frame register 1610, an analog register 1614, and a global register 1618. The load 1608 of the format register 1606 receives signals from the command register 1604. The load 1612 of the frame register 1610 receives signals from the format register 1606. The load 1616 of the analog register 1614 receives signals from the frame register 1610. The load 1620 of the global register 1618 receives signals from the analog register 1614.

FIG. 17 is a block diagram of a minimal-area image sensor for endoscopic applications in which the image sensor is incorporated into the distal end of an endo scope unit. The image sensor incorporates features disclosed herein including the features for minimizing the sensor area as described herein. Data, such as image data, is received by a pixel array 1710 of the image sensor shown in FIG. 17. A timing supervisor 1702 electronically communicates with and controls a vertical SM 1704, a programmable timing generator 1706, and a horizontal SM 1708. The timing supervisor 1702 interfaces with and controls the timing synchronization between vertical SM 1704, programmable timing generator 1706 and horizontal SM 1708 to ensure data in the pixel array 1710 is accessed and read at a particular coordinated time that is known to the system. A digital to analog converter (DAC) 1726 or charge pump on the sensor controls a DC voltage (V_(blackclamp)) and the adjustment of the black clamp level. The slow control, 2 wire protocol 1740 conveys information to the DAC 1726, reference generator, booster and bias circuit and electronically communicates with the timing supervisor 1702 to coordinate circuit timing between timing supervisor 1702 and DAC 1726.

The bandgap voltage reference 1725 is a temperature independent voltage reference circuit that produces a fixed (constant) voltage regardless of power supply variations, temperature changes and circuit loading from the imaging device. The bandgap 1725 is provided to the DAC, reference generator, booster and bias circuit 1726 and is conveyed to all blocks. The image sensor comprises a phase lock loop (PLL) 1730 that acts as a control system that generates an output signal whose phase is related to the phase of an input signal, such as a clock. The VCDL (voltage controlled delay loop) clock is compared to the incoming clock with the frequency detector and up-pushes or down-pushes are issued to the external VCO (voltage controlled oscillator) depending on the frequency detector comparison result. This system dynamically reacts and adjusts to ensure that the VCDL clock maintains synchronicity with the input clock.

PLL 1730 communicates between the image sensor and the camera control unit, by piggybacking on the communication protocol that already exists between the two devices. The frequency detector is moved from the sensor PLL to the camera control unit. Its input can then be attached to the precise clock provided by camera unit oscillator.

As shown in FIG. 17, the black clamp algorithm and the sensor correction algorithm have been moved off the image sensor. However, it will be appreciated that those algorithms may be located on the sensor as described in reference to FIG. 11. The black clamps 1714, 1715 generate black clamp signals that are received by the pin grid array (PGA) 1716, 1717 respectively. The signal processed by the pin grid array 1716, 1717 is received and processed by the analog to digital converter (ADC) 1718, 1719 respectively. In contrast with the embodiment illustrated in FIG. 11, the signal is not then processed by the black clamp algorithm or the sensor correction algorithm before the signal is serialized by the serializer 1720, 1721 respectively. A digital to analog converter or charge pump 1726 can transmit the black clamp signal to a slow control 2-wire protocol 1740.

The adjustment of the black clamp level may be done by means of controlling a DC voltage (V_(blackclamp)) using a digital to analog converter (DAC) or charge pump 1726 on the sensor. Pixel voltage offsets entering the analog to digital converters 1718, 1719 move around due to dark current in the photodiode. In some implementations, the digital to analog converters 1718, 1719 need to be regularly adjusted by assessing the black offset in the digital domain.

FIGS. 18-24 illustrate color correction methods and hardware schematics for use with a partitioned light system. It is common in digital imaging to manipulate the values within image data to correct the output to meet user expectations or to highlight certain aspects of the imaged object. In a controlled light implementation as discussed herein, calibration is important to meet the expectations of a user and check for faults within the system. One method of calibration can be a table of expected values for a given imaging condition that can be compared to the data from the sensor. An embodiment may include a color neutral scene having known values that should be output by the imaging device and the device may be adjusted to meet those known values when the device samples the color neutral scene.

FIG. 18 illustrates a process flow 1800 in which the sensor and/or emitter are adjusted to compensate for differences in energy values for the pulsed partitioned spectrums of light. In the process flow 1800, data is obtained from the histogram of a previous frame and analyzed at 1802. The sensor is adjusted at 1804 and the emitter is adjusted at 1806. The image is determined based on the adjusted sample time from the sensor at 1808, and/or the image is determined based on adjusted (either increased or decreased) emitted light at 1810.

FIG. 19 is a process flow 1900 for adjusting the sensor and recording a frame based on readings from the adjusted sensor. In the process flow 1900, a histogram of a previous frame is obtained at 1902 and the sensor is adjusted based on sensitivity at 1904. The frame is recorded at 1906 based on readings from the adjusted sensor. In an example, the process flows 1800, 1900 are implemented because the red-light spectrum is more readily detected by a sensor within the system than the blue light spectrum. In the example, the sensor is adjusted to be less sensitive during the red partition cycle and more sensitive during the blue partition cycle because of the low Quantum Efficiency the blue partition has with respect to silicon (illustrated best in FIG. 19). Similarly, the emitter may be adjusted to provide an adjusted partition (e.g., higher or lower intensity and duration).

FIG. 20 is a schematic diagram of a method 2000 for performing color correction on digital imaging in a light deficient environment. The method 2000 includes sampling a color neutral scene or value palate (see 2010) at startup by running a full cycle of electromagnetic spectrum partitions at 2002. The lookup table 2008 is generated based on the color neutral scene or value palate 2010. The lookup table 2008 is used to determine a histogram for the frame cycles at 2008. The histogram is compared to the known or expected values at 2006 based on the color neutral scene or value palate 2010 and further based on the lookup table 2008. The method includes adjusting settings on the image signal processor (ISP) at 2012 and/or adjusting the emitter at 2014. The adjustment of the emitter at 2014 may include adjustments to any aspect of the emitted light such as magnitude, duration (i.e., time-on), or the range within the spectrum partition.

It should be noted that because each partitioned spectrum of light may have different energy values, the sensor and/or light emitter may be adjusted to compensate for the differences in the energy values. For example, in an embodiment, because the blue light spectrum has a lower quantum efficiency than the red-light spectrum with regard to silicon-based imagers, the sensor's responsiveness can then be adjusted to be less responsive during the red cycle and more responsive during the blue cycle. Conversely, the emitter may emit blue light at a higher intensity, because of the lower quantum efficiency of the blue light, than red light to produce a correctly exposed image.

FIG. 21 is a schematic diagram of a method 2100 for performing fractionalized adjustments to the image signal processor (ISP) and/or emitter to reduce the amount of noise and artifacts within the outputted image stream or video. The method 2100 includes emitting and sensing a full cycle of electromagnetic spectrum partitions at 2102. The results from the full cycle of electromagnetic partitions are compared to the desired output at 2104. Based on this comparison, the image signal processor (ISP) is adjusted at 2106 and/or the emitter is adjusted at 2108. The adjustments made to the ISP at 2106 and/or the emitter at 2108 between frame cycles may be limited at 2110. For example, the emitter may be adjusted by a fraction of its operational range at any time between frames. Likewise, the ISP may be adjusted by a fraction of its operational range at any time between frames. In an embodiment, both the emitter and the ISP are limited such that they may only be adjusted together at a fraction of their respective operational ranges at any time between frames. The result of these fractional adjustments is compared at 2112 and the adjustments are finalized based on this comparison.

In an exemplary embodiment, a fractional adjustment of the ISP and/or the emitter are performed at about 0.1 dB of the operational range of the components to correct the exposure of the previous frame. The 0.1 dB is merely an example and it should be noted that is other embodiments the allowed adjustment of the components may be any portion of their respective operational ranges. The components of the system can change by intensity or duration adjustment that is generally governed by the number of bits (resolution) output by the component. The component resolution may be typically between a range of about 10-24 bits but should not be limited to this range as it is intended to include resolutions for components that are yet to be developed in addition to those that are currently available. For example, after a first frame it is determined that the scene is too blue when observed, then the emitter may be adjusted to decrease the magnitude or duration of the pulse of the blue light during the blue cycle of the system by a fractional adjustment as discussed above, such as about 0.1 dB.

In this exemplary embodiment, more than 10 percent may have been needed, but the system has limited itself to 0.1 dB adjustment of the operational range per system cycle. Accordingly, during the next system cycle the blue light can then be adjusted again, if needed. Fractionalized adjustment between cycles may have a damping effect of the outputted imaged and will reduce the noise and artifacts when operating emitters and sensors at their operation extremes. It may be determined that any fractional amount of the components' operational range of adjustment may be used as a limiting factor, or it may be determined that certain embodiments of the system may comprise components that may be adjusted over their entire operational range.

Additionally, the optical black area of any image sensor may be used to aid in image correction and noise reduction. In an embodiment, the values read from the optical black area may be compared to those of the active pixel region of a sensor to establish a reference point to be used in image data processing. FIG. 22 shows the kind of sensor correction processes that might be employed in a color pulsed system. CMOS image sensors typically have multiple non-idealities such as fixed pattern noise (FPN) and line noise. Being in total control of the illumination has the benefit that entire frames of dark data may periodically be acquired and used to correct for the pixel and column offsets.

FPN is a dispersion in the offsets of the sense elements that is typically caused by pixel to pixel dispersion stemming from random variations in dark current from photodiode to photodiode. Column fixed pattern noise is caused by offsets in the readout chain associated with a particular columns of pixels and can result in perceived vertical stripes within the image.

Line noise is a stochastic temporal variation in the offsets of pixels within each row. Because line noise is temporal, the correction must be computed anew for each line and each frame. For this purpose, there are usually many optically blind (OB) pixels within each row in the array, which must first be sampled to assess the line offset before sampling the light sensitive pixels. The line offset is then subtracted during the line noise correction process.

In the example in FIG. 22, there are other corrections concerned with getting the data into the proper order, monitoring and controlling the voltage offset in the analog domain (black clamp) and identifying/correcting individual defective pixels. The process flow 2200 includes cycling the sensor at 2202 through each of the electromagnetic partitions at a first intensity of emission. The process flow 2200 includes cycling the sensor at 2204 through each of the electromagnetic partitions at a second intensity of emission. The process flow 2200 includes combining at 2206 the data from the electromagnetic partitions at the first intensity of emission and the second intensity of emission.

FIG. 23 is a schematic diagram of a process flow 2300 for increasing dynamic range of a resultant image. The process flow 2300 includes cycling the sensor at 2302 through each of the electromagnetic partitions at a first intensity of emission. The process flow 2300 includes cycling the sensor at 2304 through each of the electromagnetic partitions at a second intensity of emission. The process flow 2300 includes cycling at 2306 the sensor through “n” electromagnetic partitions at an “m” intensity of emission and may be repeated any suitable number of times. The process flow 2300 includes cycling the sensor at 2308 through “n+i” electromagnetic partitions at an “m+j” intensity of emission. The process flow 2300 includes combining at 2310 data from each of the cycled emission intensities.

In an embodiment, exposure inputs may be input at different levels over time and combined to produce greater dynamic range. Greater dynamic range may be especially desirable because of the limited space environment in which an imaging device is used. In limited space environments that are light deficient or dark, except for the light provided by the light source, and where the light source is close to the light emitter, exposure has an exponential relationship to distance. For example, objects near the light source and optical opening of the imaging device tend to be over exposed, while objects farther away tend to be extremely under exposed because there is very little (in any) ambient light present.

As can be seen in FIG. 23, the cycles of a system having emissions of electromagnetic energy in a plurality of partitions may be serially cycled according to the partitions of electromagnetic spectrum. For example, in an embodiment where the emitter emits lasers in a distinct red partition, a distinct blue partition, a distinct green partition, and a distinct fluorescence partition, the two cycle datasets that are going to be combined may be in the form of:

i. red at intensity one at 2302;

ii. red at intensity two at 2304;

iii. blue at intensity one at 2302;

iv. blue at intensity two at 2304;

v. green at intensity one at 2302;

vi. green at intensity two at 2304;

vii. fluorescence excitation at intensity one at 2302; and

viii. fluorescence excitation at intensity two at 2304.

Alternatively, the system may be cycled in the form of:

i. red at intensity one at 2302;

ii. blue at intensity one at 2302;

iii. green at intensity one at 2302;

iv. fluorescence excitation at intensity one at 2302;

v. red at intensity two at 2304;

vi. blue at intensity two at 2304;

vii. green at intensity two at 2304; and

viii. fluorescence excitation at intensity two at 2304.

In such an embodiment, a first image may be derived from the intensity one values, and a second image may be derived from the intensity two values, and then combined or processed as complete image datasets at 2310 rather than their component parts.

It is contemplated to be within the scope of this disclosure that any number of emission partitions may be used in any order. As seen in FIG. 23, “n” is used as a variable to denote any number of electromagnetic partitions and “m” is used to denote any level of intensity for the “n” partitions. Such a system may be cycled in the form of:

i. n at intensity m at 2306;

ii. n+1 at intensity m+1;

iii. n+2 at intensity m+2; and

iv. n+i at intensity m+j at 2308.

Accordingly, any pattern of serialized cycles can be used to produce the desired image correction wherein “i” and “j” are additional values within the operation range of the imaging system.

FIG. 24 illustrates a process flow 2400 to be implemented by a controller and/or monochrome image signal processor (ISP) for generating a video stream having RGB images with fluorescence data overlaid thereon. The image signal processor (ISP) chain may be assembled for the purpose of generating sRGB image sequences from raw sensor data, yielded in the presence of the G-R-G-B-Fluorescence light pulsing scheme. In the process flow 2400, the first stage is concerned with making corrections (see receiving data from the sensor at 2402, re-ordering at 2404, and sensor corrections at 2406 in FIG. 24) to account for any non-idealities in the sensor technology for which it is most appropriate to work in the raw data domain. At the next stage, multiple frames (for example, a green frame 2408 a, a red-blue frame 2408 b, and a fluorescence frame 2408 c) are buffered because each final frame derives data from multiple raw frames. The frame reconstruction at 1264 proceeds by sampling data from a current frame and two buffered frames (see 2408 a, 2408 b, and/or 2408 c). The reconstruction process results in full color frames in linear RGB color space that include fluorescence image data. In this example, the white balance coefficients at 2418 and color correction matrix at 2420 are applied before converting to YCbCr space at 2422 for subsequent edge enhancement at 2424. After edge enhancement at 2424, images are transformed back to linear RGB at 2426 for scaling at 2428, if applicable. Finally, the gamma transfer function at 2430 is applied to translate the data into the sRGB domain at 2432.

FIG. 25 is an example of color fusion hardware 2500. The color fusion hardware 2500 stores in memory 2504 an R-G-B-G-Fluorescence video data stream with a memory writer 2502 and converts the video data stream to a parallel RGB+Fluorescence video data stream at 2505. The bit width on the input side may be, e.g., 12 bits per color. The output width for that example would be at least 36 bits per pixel. Other embodiments may have different initial bit widths and 3+ times that number for the output width. The memory writer 2502 block takes as its input the RGBG-Fluorescence video stream and writes each frame to its correct frame memory 2504 (the memory writer triggers off the same pulse generator (see 2510) that runs the laser light source). The memory 2504 may store exposure frame data in a pattern such as the one illustrated, namely: Red, Green 1, Blue, Green 2, Fluorescence and then starts back with Red again. The memory reader 2506 reads three frames at once to construct an RGB pixel. Each pixel is three times the bit width of an individual color component. The memory reader 2506 also triggers off the laser pulse generator at 2510. In an embodiment, the memory reader 2506 waits until Red, Green 1 and Blue frames have been written, then proceeds to read them out in parallel while the writer continues writing Green 2, Fluorescence, and starts back on Red. When Red completes the reader begins reading from Blue, Green 2, Fluorescence, and Red. This pattern continues indefinitely.

FIG. 26 is a schematic diagram of a process flow 2600 for sensor correction processes. The process flow 2600 is an example implementation of the front end of an image signal process that has been developed in the context of a system incorporating a minimal area image sensor. In the example process flow 2600, there are two digitizers on the sensor converting the even and odd-numbered columns respectively and transmitting serial data on two differential ports. The process flow 2600 may be employed in a color and fluorescence pulsed system as discussed herein. The process flow 2600 may be employed to counteract non-idealities in CMOS image sensors such as fixed pattern noise (FPN) and line noise. Fixed pattern noise is a dispersion in the offsets of the sense elements. Typically, most of the FPN is a pixel to pixel dispersion which stems from random variations in dark current from photodiode to photodiode. The systems disclosed herein maintain complete control of the illumination source, and this enables dark data to be acquired and used to correct for the pixel and column offsets. In the illustrated example, a single frame buffer may be used to make a running average of the whole frame without light using, e.g., simple exponential smoothing. This dark average frame may be subtracted from every illuminated frame during regular operation. Line noise is a stochastic temporal variation in the offsets of pixels within each row. Because line noise is temporal, the correction is computed for each line and each frame. For this purpose, there are usually many optically blind (OB) pixels within each row in a pixel array. The OB pixels must first be sampled to assess the line offset before sampling the light sensitive pixels. The line offset is then subtracted during the line noise correction process.

The process flow 2600 includes performing top deserialization 2602 and bottom deserialization 2603. The process flow 2600 includes performing line reordering at the top port at 2604 and line reordering at the bottom port at 2605. The information may be stored in separate databases 2632, 2634 or other memory devices upon the completion of line reordering. The process flow 2600 includes performing a black clamp calculation on the top ADC at 2606 and a black clamp calculation on the bottom ADC at 2607. The information exits the process flow 2600 on a first-in-first-out (FIFO) basis. The process flow 2600 includes performing line noise correction at the top ADC at 2608 and line noise correction at the bottom ADC at 2609. The process flow 2600 includes performing full line recombination at 2610 and dark frame accumulation at 2612. The information may be stored in a database 2630 or other memory device before fixed pattern noise (FPN) correction is performed. The process flow includes performing fixed pattern noise (FPN) correction at 2614 and pixel defect correction at 2616. The process flow 2600 includes performing programmable digital gain at 2618 before a video stream exits the process flow 2600 to be provided to a user.

Individual optical black pixels which do not behave normally may badly degrade the quality of the black offset measurements. An approach disclosed herein includes computing the media of a group of five pixels for each optical black pixel. The five pixels include the pixel in question and its four nearest neighbors. The final line offset estimate may then be computed as the mean of all the medians. In an embodiment, some provisions are made to avoid losing statistics at the beginning and the end. Such provisions include buffering the whole sample of optical blacks and wrapping around the sample of five. Buffering necessitates pipelining the data and results in a delay equal to at least the total number of optical blacks per analog to digital converter channel, per row.

The line offset estimate for an even channel (assuming two analog to digital converters with odd-even interspersion), row #r can be computed as follows:

$L_{r,{{ev}en}} = \frac{2 \cdot {\sum_{{{i = 0},2,{4\ldots}}\;}^{N_{OB} - 2}\mu_{i}}}{N_{OB}}$

The line offset where N_(OB) may be the total number of optical black pixels per row and μ_(i) may be the median for optical black pixel i, computed thus:

μ₀ = median  [x_((N_(OB) − 4)), x_((N_(OB) − 2)), x₀, x₂, x₄] μ₂ = median  [x_((N_(OB) − 2)), x₀, x₂, x₄, x₆] μ₄ = median  [x₀, x₂, x₄, x₆, x₈]           ⋯ μ_((N_(OB) − 2)) = median  [x_((N_(OB) − 6)), x_((N_(OB) − 4)), x_((N_(OB) − 2)), x₀, x₂]

Likewise, the line offset estimate for an odd channel (assuming two analog to digital converters with odd-even interspersion), row #r can be computed as follows:

$L_{r,{odd}} = \frac{2 \cdot {\sum_{{{i = 1},3,{5\ldots}}\;}^{N_{OB} - 1}\mu_{i}}}{N_{OB}}$ where μ₁ = median  [x_((N_(OB) − 3)), x_((N_(OB) − 1)), x₁, x₃, x₅] μ₃ = median  [x_((N_(OB) − 1)), x₁, x₃, x₅, x₇] μ₅ = median  [x₁, x₃, x₅, x₇, x₉]           ⋯ μ_((N_(OB) − 1)) = median  [x_((N_(OB) − 5)), x_((N_(OB) − 3)), x_((N_(OB) − 1)), x₁, x₃]

The overall frame black level may be computed by accumulating each of the line offsets to compute the overall black level. In this approach, the overall black level is determined using simple exponential smoothing (SES). Simple exponential smoothing allows the rows at the end of the frame to have a greater influence on the final black estimate. This may be desirable in certain implementations for addressing changes in black offset occurring on sub-frame timescales. The simple exponential smoothing algorithm determines a running estimate that may be incrementally adjusted each time a sample is made available. For convenience the sample can be divided by a binary number (2^(q)) before being added to the previous estimate. The previous estimate may be first multiplied by (2^(q)-1)/2^(q) each time, in order to normalize the result. High values of q result in greater statistical precision over time in a stable scenario. Lower values of q may make the correction more reactive to rapid changes. q should be made available as a tunable parameter. This may be computed as follows:

${k_{r} = {L_{r}\left( {r = 0} \right)}}{k_{r} = {{\frac{1}{2^{q}}L_{r}} + {\frac{\left( {2^{q} - 1} \right)}{2^{q}}{k_{({r - 1})}\left( {r > 0} \right)}}}}$ where k_(r) is the black level estimate after row r and L_(r) may be the line offset estimate for row r. The decision about what to do with the black clamp digital to analog converters may be made after the final row in the array has been added.

The black clamp algorithm at 2606, 2607 may require a target black level, and this can be provided by an adjustable parameter. The black clamp digital to analog converter on the sensor for the channel in question would be pushed up or down depending on whether the observed black estimate may be above or below the target. The size of the push could be the smallest unit, i.e. one digital to analog converter count, provided the black offset may be close to the target. In the case that the black level may be a long way from the target, a larger proportional push could be made. The algorithm would need to know a rough calibration of the correspondence between black clamp digital to analog converter counts and sensor analog to digital converter counts and the directionality of digital to analog converter adjustments with respect to the output black level.

The line noise is corrected at 2608 and 2609. Line noise refers to stochastic, temporal variations in the offset of a horizontal row of pixels. There may be multiple sources, but it can be considered as reset noise arising from analog elements being reset each time a row of pixels is read out. It may be temporal, and a new correction should be computed for each new line per every frame. Since the amplification stage at the analog to digital converter input may be the final analog element, there may be good reason to suspect that the line noise appears phenomenologically independent per analog to digital converter channel. One approach is to correct each analog to digital converter channel separately.

It can be challenging to completely eliminate line noise because the sample of optical black pixels used for the line offset estimate may be separate from the sample to which the correction may be applied. The sample statistics are finite. Assuming the noise is Gaussian, the post-correction line noise may be approximately equal to the uncertainty in the line offset estimate arising from the pixel temporal noise present in the optical black pixels:

$\sigma_{L,{post}} \approx \frac{\sigma_{P}}{\sqrt{N_{OB}}}$ where σ_(L,post) is the post correction temporal line noise, σ_(P) is optical black pixel temporal noise, and N_(OB) is the number of optical black pixels. The line noise correction also introduces a spatial line noise component, mostly as a consequence of the pixel fixed pattern noise present within the optical black pixels:

${FPN_{L,{post}}} \approx \frac{FPN_{P}}{\sqrt{N_{OB}}}$

This artifact can be eliminated by the fixed pattern noise correction later in the chain. Simulations have indicated that in order for temporal line noise to be invisible, the magnitude should be less than approximately 1/10 of the pixel temporal noise.

Line-noise correction application to optically sighted (clear) pixels: x′ _(i) =x _(i) −L+B where L is the line offset estimate for the current line, ported from the ‘Black Clamp’ module and B is the black clamp target level.

Full line recombination at 2610 includes combining the two data channels (i.e., the top data channel and the bottom data channel) into a full line. The top and bottom data channels need to be interleaved in such a way that the final clear pixel order reflects the correct order in the array.

The fixed pattern noise correction at 2614 includes adjusting a running offset estimate on a per physical pixel basis. CMOS image sensors have multiple noise sources. The magnitude and appearance of noise depends on a range of physical conditions. Pure Poisson or Gaussian temporal noise with no coherent components (e.g. photon shot noise or source follower 1/f read noise) looks as natural as noise can look. All other perceivable noise types may degrade the image quality to a greater extent for the same amplitude. Spatial noise (fixed pattern noise) may be especially damaging and CMOS sensors inherently have at least two sources. CMOS image sensors experience pixel fixed pattern noise and column fixed pattern noise. The pixel fixed pattern noise may be mostly due to variations in photodiode leakage current (dark signal) from pixel to pixel (DSNU). This source may be exponentially dependent on junction temperature (T_(J)) and linearly dependent on exposure time. Column fixed pattern noise may be a consequence of the readout architecture, in which pixels from within the same column are channeled through common analog readout elements.

Typically, an on-chip digital fixed pattern noise correction involves dealing only with the column fixed pattern noise component and requires one offset correction register per column. The precision of such a correction might typically be 20 bits or so per column, which translates to around 5 kB of RAM for a 1920×1080 array. One of the benefits of migrating the digital sensor corrections to the image signal processor may be the ready availability of RAM. This opens up the possibility of a comprehensive fixed pattern noise correction which cancels out any row, column or pixel-wise component. This may be accomplished by means of simple exponential smoothing (SES) in which each fresh dark frame sample may be used to adjust a running offset estimate on a per physical pixel basis.

The programmable digital gain 2618 may be executed by a programmable digital amplifier. CMOS image sensors are usually equipped with digital programmable gain stages with very fine increments. This may be to facilitate auto exposure processes which typically modulate the gain and the exposure time. The programmable digital amplifier can be used to align the range of the sensor analog to digital converter to the range of the image signal processor (e.g. ×2 for 11 bit analog to digital converter to 12-bit image signal processor). A small amount of digital gain may also be used to trim off the imprint of the digital line noise and fixed pattern noise corrections which becomes apparent at the full range of the analog to digital converter.

A more space conservative approach involves combining large amounts of control RAM into single, long registers. In the extreme case, all parameters could be placed into a single register, requiring no address ROM. This solution may be not very practical because writing control registers takes time and typical video applications involve changing a small number of operational parameters on a frame-by-frame basis. The most practical solution may be afforded by concatenating functionally related sets of parameters into a small number of long registers. The difference in space implied by having ten registers (requiring 4 address bits) versus one may be negligible. In particular it makes sense that all of the parameters which are written periodically at a high rate belong together in an exclusive register (the frame register), in order to keep the time required to write it to a minimum. Such parameters include the exposure times, gains, incremental offset adjustments and any others necessary to maintain continuous high-quality video. If the digital data-path logic has been migrated off chip as described earlier, the black clamp voltage adjustment data also belongs in such a register since it should be revised every frame too. In an implementation, during this configuration phase can registers be written and therefore the timing of the frame register writes with respect to the overall frame timing should be carefully controlled by the camera.

Other examples of parametric register groupings could include; analog currents, analog voltages, pixel timing, vertical timing, sensor commands (resets etc.) and so on. In FIG. 15, the arrangement of registers may be shown for a specific minimal-area sensor design. The “Command” register may be used for top level event-oriented 1-bit commands such as chip resets and the loads for the other registers shown below it. A 2-wire protocol address decoder decides which shift register to direct incoming 2-wire protocol data toward. To load the “Format” register, e.g., the external controller sends a command with the address associated with the Format register. This places the stream of data into the Format-register shift register. Then in order to latch the data, a follow up command may be sent to the Command register with the particular “load Format” bit set. It will be appreciated that a plurality of control registers may be used. The control registers may be digital latches that may be loaded via shift registers. The shift registers may be arbitrary in length. In an embodiment, a majority of the plurality of control registers may be loaded using shift registers that include many tens of bits. In an embodiment, a majority of the plurality of control registers may be loaded using shift registers that include hundreds of bits. In an embodiment, a majority of the plurality of control registers may be loaded using shift registers that include thousands of bits. In an embodiment, the shift registers may be loaded using a serial, 2-wire protocol. In an embodiment, one of the shift registers may be dedicated to frame-to-frame parameter changes, such as, e.g., integration times and black clamp offset adjustments.

FIG. 27 is a schematic diagram of a pattern reconstruction process. The example pattern illustrated in FIG. 27 includes Red, Green, Blue, and Fluorescence pulses of light that each last a duration of T1. In various embodiments, the pulses of light may be of the same duration or of differing durations. The Red, Green, Blue, and Fluorescence exposure frames are combined to generate an RGB image with fluorescence data overlaid thereon. A single image frame comprising a red exposure frame, a green exposure frame, a blue exposure frame, and a fluorescence exposure frame requires a time period of 4*T1 to be generated. The time durations shown in FIG. 27 are illustrative only and may vary for different implementations. In other embodiments, different pulsing schemes may be employed. For example, embodiments may be based on the timing of each color component or frame (T1) and the reconstructed frame having a period twice that of the incoming color frame (2×T1). Different frames within the sequence may have different frame periods and the average capture rate could be any multiple of the final frame rate.

In an embodiment, the dynamic range of the system is increased by varying the pixel sensitivities of pixels within the pixel array of the image sensor. Some pixels may sense reflected electromagnetic radiation at a first sensitivity level, other pixels may sense reflected electromagnetic radiation at a second sensitivity level, and so forth. The different pixel sensitivities may be combined to increase the dynamic range provided by the pixel configuration of the image sensor. In an embodiment, adjacent pixels are set at different sensitivities such that each cycle includes data produced by pixels that are more and less sensitive with respect to each other. The dynamic range is increased when a plurality of sensitivities are recorded in a single cycle of the pixel array. In an embodiment, wide dynamic range can be achieved by having multiple global TX, each TX firing only on a different set of pixels. For example, in global mode, a global TX1 signal is firing a set 1 of pixels, a global TX2 signal is firing a set 2 of pixel, a global TXn signal is firing a set n of pixels, and so forth.

FIG. 28A illustrates a timing example for two different pixel sensitivities (dual pixel sensitivity) in a pixel array. In this case, global TX1 signal fires half of the pixels of the array and global TX2 fires the other half of the pixels. Because global TX1 and global TX2 have different “on” to “off” edge positions, and integrated light is different between the TX1 pixels and the TX2 pixels.

FIG. 28B illustrates a different embodiment of the timing for dual pixel sensitivity. In this case, the light pulse is modulated twice (pulse duration and/or amplitude). TX1 pixels integrate P1 pulse and TX2 pixels integrate P1+P2 pulses. Separating global TX signals can be done many ways, including differentiating TX lines from each row, and sending multiple TX lines per row with each TX line addressing a different set of pixels.

FIGS. 29A-29C illustrate the use of a white light emission that is pulsed and/or synced, or held constant, with a corresponding color sensor. As can be seen in FIG. 29A, a white light emitter may be configured to emit a beam of light during the blanking period of a corresponding sensor to provide a controlled light source in a controlled light environment. The light source may emit a beam at a constant magnitude and vary the duration of the pulse as seen in FIG. 29A, or may hold the pulse constant with varying the magnitude to achieve correctly exposed data as illustrated in FIG. 29B. Illustrated in FIG. 29C is a graphical representation of a constant light source that can be modulated with varying current that is controlled by and synced with a sensor.

In an embodiment, white light or multi-spectrum light is emitted as a pulse to provide data for use within the system (illustrated best in FIGS. 29A-29C). White light emissions in combination with partitions of the electromagnetic spectrum may be useful for emphasizing and de-emphasizing certain aspects within a scene. Such an embodiment might use a pulsing pattern of:

i. Green pulse;

ii. Red pulse;

iii. Blue pulse;

iv. Fluorescence excitation pulse;

v. Green pulse;

vi. Red pulse;

vii. Blue pulse;

viii. Fluorescence excitation pulse;

ix. (Repeat)

Any system using an image sensor cycle that is at least two times faster than the white light cycle is intended to fall within the scope of the disclosure. It will be appreciated that any combination of partitions of the electromagnetic spectrum is contemplated herein, whether it be from the visible or non-visible spectrum of the full electromagnetic spectrum.

FIGS. 30A-30C each illustrate a light source 3000 having a plurality of emitters. The emitters include a first emitter 3002, a second emitter 3004, and a third emitter 3006. Additional emitters may be included, as discussed further below. The emitters 3002, 3004, and 3006 may include one or more laser emitters that emit light having different wavelengths. For example, the first emitter 3002 may emit a wavelength that is consistent with a blue laser, the second emitter 3004 may emit a wavelength that is consistent with a green laser, and the third emitter 3006 may emit a wavelength that is consistent with a red laser. For example, the first emitter 3002 may include one or more blue lasers, the second emitter 3004 may include one or more green lasers, and the third emitter 3006 may include one or more red lasers. The emitters 3002, 3004, 3006 emit laser beams toward a collection region 3008, which may be the location of a waveguide, lens, or other optical component for collecting and/or providing light to a waveguide, such as the jumper waveguide 206 or lumen waveguide 210 of FIG. 2.

In an implementation where a patient has been administered a reagent or dye to aid in the identification of certain tissues, structures, chemical reactions, biological processes, and so forth, the emitters 3002, 3004, and 3006 may emit wavelength(s) for fluorescing the reagents or dyes. Such wavelength(s) may be determined based on the reagents or dyes administered to the patient. In such an embodiment, the emitters may need to be highly precise for emitting desired wavelength(s) to fluoresce or activate certain reagents or dyes.

In an implementation, the emitters 3002, 3004, and 3006 emit a laser scanning pattern for mapping a topology of a scene and/or for calculating dimensions and distances between objects in the scene. In an embodiment, the endoscopic imaging system is used in conjunction with multiple tools such as scalpels, retractors, forceps, and so forth. In such an embodiment, each of the emitters 3002, 3004, and 3006 may emit a laser scanning pattern such that a laser scanning pattern is projected on to each tool individually. In such an embodiment, the laser scanning data for each of the tools can be analyzed to identify distances between the tools and other objects in the scene.

In the embodiment of FIG. 30B, the emitters 3002, 3004, 3006 each deliver laser light to the collection region 3008 at different angles. The variation in angle can lead to variations where electromagnetic energy is located in an output waveguide. For example, if the light passes immediately into a fiber bundle (glass or plastic) at the collection region 3008, the varying angles may cause different amounts of light to enter different fibers. For example, the angle may result in intensity variations across the collection region 3008. Furthermore, light from the different emitters may not be homogenously mixed so some fibers may receive different amounts of light of different colors. Variation in the color or intensity of light in different fibers can lead to non-optimal illumination of a scene. For example, variations in delivered light or light intensities may result at the scene and captured images.

In one embodiment, an intervening optical element may be placed between a fiber bundle and the emitters 3002, 3004, 3006 to mix the different colors (wavelengths) of light before entry into the fibers or other waveguide. Example intervening optical elements include a diffuser, mixing rod, one or more lenses, or other optical components that mix the light so that a given fiber receive a same amount of each color (wavelength). For example, each fiber in the fiber bundle may have a same color. This mixing may lead to the same color in each fiber but may, in some embodiments, still result in different total brightness delivered to different fibers. In one embodiment, the intervening optical element may also spread out or even out the light over the collection region so that each fiber carries the same total amount of light (e.g., the light may be spread out in a top hat profile). A diffuser or mixing rod may lead to loss of light.

Although the collection region 3008 is represented as a physical component in FIG. 30A, the collection region 3008 may simply be a region where light from the emitters 3002, 3004, and 3006 is delivered. In some cases, the collection region 3008 may include an optical component such as a diffuser, mixing rod, lens, or any other intervening optical component between the emitters 3002, 3004, 3006 and an output waveguide.

FIG. 30C illustrates an embodiment of a light source 3000 with emitters 3002, 3004 3006 that provide light to the collection region 3008 at the same or substantially same angle. The light is provided at an angle substantially perpendicular to the collection region 3008. The light source 3000 includes a plurality of dichroic mirrors including a first dichroic mirror 3010, a second dichroic mirror 3012, and a third dichroic mirror 3014. The dichroic mirrors 3010, 3012, 3014 include mirrors that reflect a first wavelength of light but transmit (or are transparent to) a second wavelength of light. For example, the third dichroic mirror 3014 may reflect blue laser light provided by the third emitter, while being transparent to the red and green light provided by the first emitter 3002 and the second emitter 3004, respectively. The second dichroic mirror 3012 may be transparent to red light from the first emitter 3002, but reflective to green light from the second emitter 3004. If other colors or wavelengths are included dichroic mirrors may be selected to reflect light corresponding to at least one emitter and be transparent to other emitters. For example, the third dichroic mirror 3014 reflect the light form the third emitter 3006 but is to emitters “behind” it, such as the first emitter 3002 and the second emitter 3004. In embodiments where tens or hundreds of emitters are present, each dichroic mirror may be reflective to a corresponding emitter and emitters in front of it while being transparent to emitters behind it. This may allow for tens or hundreds of emitters to emit electromagnetic energy to the collection region 3008 at a substantially same angle.

Because the dichroic mirrors allow other wavelengths to transmit or pass through, each of the wavelengths may arrive at the collection region 3008 from a same angle and/or with the same center or focal point. Providing light from the same angle and/or same focal/center point can significantly improve reception and color mixing at the collection region 3008. For example, a specific fiber may receive the different colors in the same proportions they were transmitted/reflected by the emitters 3002, 3004, 3006 and mirrors 3010, 3012, 3014. Light mixing may be significantly improved at the collection region compared to the embodiment of FIG. 30B. In one embodiment, any optical components discussed herein may be used at the collection region 3008 to collect light prior to providing it to a fiber or fiber bundle.

FIG. 30C illustrates an embodiment of a light source 3000 with emitters 3002, 3004, 3006 that also provide light to the collection region 3008 at the same or substantially same angle. However, the light incident on the collection region 3008 is offset from being perpendicular. Angle 3016 indicates the angle offset from perpendicular. In one embodiment, the laser emitters 3002, 3004, 3006 may have cross sectional intensity profiles that are Gaussian. As discussed previously, improved distribution of light energy between fibers may be accomplished by creating a more flat or top-hat shaped intensity profile. In one embodiment, as the angle 3016 is increased, the intensity across the collection region 3008 approaches a top hat profile. For example, a top-hat profile may be approximated even with a non-flat output beam by increasing the angle 3016 until the profile is sufficiently flat. The top hat profile may also be accomplished using one or more lenses, diffusers, mixing rods, or any other intervening optical component between the emitters 3002, 3004, 3006 and an output waveguide, fiber, or fiber optic bundle.

FIG. 31 is a schematic diagram illustrating a single optical fiber 3102 outputting via a diffuser 3104 at an output. In one embodiment, the optical fiber 3102 has a diameter of 500 microns, a numerical aperture of 0.65, and emits a light cone 3106 of about 70 or 80 degrees without a diffuser 3104. With the diffuser 3104, the light cone 3106 may have an angle of about 110 or 120 degrees. The light cone 3106 may be a majority of where all light goes and is evenly distributed. The diffuser 3104 may allow for more even distribution of electromagnetic energy of a scene observed by an image sensor.

In one embodiment, the lumen waveguide 210 includes a single plastic or glass optical fiber of about 500 microns. The plastic fiber may be low cost, but the width may allow the fiber to carry a sufficient amount of light to a scene, with coupling, diffusion, or other losses. For example, smaller fibers may not be able to carry as much light or power as a larger fiber. The lumen waveguide 210 may include a single or a plurality of optical fibers. The lumen waveguide 210 may receive light directly from the light source or via a jumper waveguide. A diffuser may be used to broaden the light output 206 for a desired field of view of the image sensor 214 or other optical components.

Although three emitters are shown in FIGS. 30A-30C, emitters numbering from one into the hundreds or more may be used in some embodiments. The emitters may have different wavelengths or spectrums of light that they emit, and which may be used to contiguously cover a desired portion of the electromagnetic spectrum (e.g., the visible spectrum as well as infrared and ultraviolet spectrums). The emitters may be configured to emit visible light such as red light, green light, and blue light, and may further be configured to emit hyperspectral emissions of electromagnetic radiation, fluorescence excitation wavelengths for fluorescing a reagent, and/or laser mapping patterns for calculating parameters and distances between objects in a scene.

FIG. 32 illustrates a portion of the electromagnetic spectrum 3200 divided into twenty different sub-spectrums. The number of sub-spectrums is illustrative only. In at least one embodiment, the spectrum 3200 may be divided into hundreds of sub-spectrums, each with a small waveband. The spectrum may extend from the infrared spectrum 3202, through the visible spectrum 3204, and into the ultraviolet spectrum 3206. The sub-spectrums each have a waveband 3208 that covers a portion of the spectrum 3200. Each waveband may be defined by an upper wavelength and a lower wavelength.

Hyperspectral imaging includes imaging information from across the electromagnetic spectrum 3200. A hyperspectral pulse of electromagnetic radiation may include a plurality of sub-pulses spanning one or more portions of the electromagnetic spectrum 3200 or the entirety of the electromagnetic spectrum 3200. A hyperspectral pulse of electromagnetic radiation may include a single partition of wavelengths of electromagnetic radiation. A resulting hyperspectral exposure frame includes information sensed by the pixel array subsequent to a hyperspectral pulse of electromagnetic radiation. Therefore, a hyperspectral exposure frame may include data for any suitable partition of the electromagnetic spectrum 3200 and may include multiple exposure frames for multiple partitions of the electromagnetic spectrum 3200. In an embodiment, a hyperspectral exposure frame includes multiple hyperspectral exposure frames such that the combined hyperspectral exposure frame comprises data for the entirety of the electromagnetic spectrum 3200.

In one embodiment, at least one emitter (such as a laser emitter) is included in a light source (such as the light sources 202, 3000) for each sub-spectrum to provide complete and contiguous coverage of the whole spectrum 3200. For example, a light source for providing coverage of the illustrated sub-spectrums may include at least 20 different emitters, at least one for each sub-spectrum. In one embodiment, each emitter covers a spectrum covering 40 nanometers. For example, one emitter may emit light within a waveband from 500 nm to 540 nm while another emitter may emit light within a waveband from 540 nm to 580 nm. In another embodiment, emitters may cover other sizes of wavebands, depending on the types of emitters available or the imaging needs. For example, a plurality of emitters may include a first emitter that covers a waveband from 500 to 540 nm, a second emitter that covers a waveband from 540 nm to 640 nm, and a third emitter that covers a waveband from 640 nm to 650 nm. Each emitter may cover a different slice of the electromagnetic spectrum ranging from far infrared, mid infrared, near infrared, visible light, near ultraviolet and/or extreme ultraviolet. In some cases, a plurality of emitters of the same type or wavelength may be included to provide sufficient output power for imaging. The number of emitters needed for a specific waveband may depend on the sensitivity of a monochrome sensor to the waveband and/or the power output capability of emitters in that waveband.

The waveband widths and coverage provided by the emitters may be selected to provide any desired combination of spectrums. For example, contiguous coverage of a spectrum using very small waveband widths (e.g., 10 nm or less) may allow for highly selective hyperspectral and/or fluorescence imaging. The waveband widths may allow for selectively emitting the excitation wavelength(s) for one or more particular fluorescent reagents. Additionally, the waveband widths may allow for selectively emitting certain partitions of hyperspectral electromagnetic radiation for identifying specific structures, chemical processes, tissues, biological processes, and so forth. Because the wavelengths come from emitters which can be selectively activated, extreme flexibility for fluorescing one or more specific fluorescent reagents during an examination can be achieved. Additionally, extreme flexibility for identifying one or more objects or processes by way of hyperspectral imaging can be achieved. Thus, much more fluorescence and/or hyperspectral information may be achieved in less time and within a single examination which would have required multiple examinations, delays because of the administration of dyes or stains, or the like.

FIG. 33 is a schematic diagram illustrating a timing diagram 3300 for emission and readout for generating an image. The solid line represents readout (peaks 3302) and blanking periods (valleys) for capturing a series of exposure frames 3304-3314. The series of exposure frames 3304-3314 may include a repeating series of exposure frames which may be used for generating laser scanning, hyperspectral, and/or fluorescence data that may be overlaid on an RGB video stream. In an embodiment, a single image frame comprises information from multiple exposure frames, wherein one exposure frame includes red image data, another exposure frame includes green image data, and another exposure frame includes blue image data. Additionally, the single image frame may include one or more of hyperspectral image data, fluorescence image data, and laser scanning data. The multiple exposure frames are combined to produce the single image frame. The single image frame is an RGB image with hyperspectral imaging data. The series of exposure frames include a first exposure frame 3304, a second exposure frame 3306, a third exposure frame 3308, a fourth exposure frame 3310, a fifth exposure frame 3312, and an Nth exposure frame 3326.

Additionally, the hyperspectral image data, the fluorescence image data, and the laser scanning data can be used in combination to identify critical tissues or structures and further to measure the dimensions of those critical tissues or structures. For example, the hyperspectral image data may be provided to a corresponding system to identify certain critical structures in a body such as a nerve, ureter, blood vessel, cancerous tissue, and so forth. The location and identification of the critical structures may be received from the corresponding system and may further be used to generate topology of the critical structures using the laser scanning data. For example, a corresponding system determines the location of a cancerous tumor based on hyperspectral imaging data. Because the location of the cancerous tumor is known based on the hyperspectral imaging data, the topology and distances of the cancerous tumor may then be calculated based on laser scanning data. This example may also apply when a cancerous tumor or other structure is identified based on fluorescence imaging data.

In one embodiment, each exposure frame is generated based on at least one pulse of electromagnetic energy. The pulse of electromagnetic energy is reflected and detected by an image sensor and then read out in a subsequent readout (3302). Thus, each blanking period and readout results in an exposure frame for a specific spectrum of electromagnetic energy. For example, the first exposure frame 3304 may be generated based on a spectrum of a first one or more pulses 3316, a second exposure frame 3306 may be generated based on a spectrum of a second one or more pulses 3318, a third exposure frame 3308 may be generated based on a spectrum of a third one or more pulses 3320, a fourth exposure frame 3310 may be generated based on a spectrum of a fourth one or more pulses 3322, a fifth exposure frame 3312 may be generated based on a spectrum of a fifth one or more pulses 3324, and an Nth exposure frame 3326 may be generated based on a spectrum of an Nth one or more pulses 3326.

The pulses 3316-3326 may include energy from a single emitter or from a combination of two or more emitters. For example, the spectrum included in a single readout period or within the plurality of exposure frames 3304-3314 may be selected for a desired examination or detection of a specific tissue or condition. According to one embodiment, one or more pulses may include visible spectrum light for generating an RGB or black and white image while one or more additional pulses are emitted to sense a spectral response to a hyperspectral wavelength of electromagnetic radiation. For example, pulse 3316 may include red light, pulse 3318 may include blue light, and pulse 3320 may include green light while the remaining pulses 3322-3326 may include wavelengths and spectrums for detecting a specific tissue type, fluorescing a reagent, and/or mapping the topology of the scene. As a further example, pulses for a single readout period include a spectrum generated from multiple different emitters (e.g., different slices of the electromagnetic spectrum) that can be used to detect a specific tissue type. For example, if the combination of wavelengths results in a pixel having a value exceeding or falling below a threshold, that pixel may be classified as corresponding to a specific type of tissue. Each frame may be used to further narrow the type of tissue that is present at that pixel (e.g., and each pixel in the image) to provide a very specific classification of the tissue and/or a state of the tissue (diseased/healthy) based on a spectral response of the tissue and/or whether a fluorescent reagent is present at the tissue.

The plurality of frames 3304-3314 is shown having varying lengths in readout periods and pulses having different lengths or intensities. The blanking period, pulse length or intensity, or the like may be selected based on the sensitivity of a monochromatic sensor to the specific wavelength, the power output capability of the emitter(s), and/or the carrying capacity of the waveguide.

In one embodiment, dual image sensors may be used to obtain three-dimensional images or video feeds. A three-dimensional examination may allow for improved understanding of a three-dimensional structure of the examined region as well as a mapping of the different tissue or material types within the region.

In an example implementation, a fluorescent reagent is provided to a patient, and the fluorescent reagent is configured to adhere to cancerous cells. The fluorescent reagent is known to fluoresce when radiated with a specific partition of electromagnetic radiation. The relaxation wavelength of the fluorescent reagent is also known. In the example implementation, the patient is imaged with an endoscopic imaging system as discussed herein. The endoscopic imaging system pulses partitions of red, green, and blue wavelengths of light to generate an RGB video stream of the interior of the patient's body. Additionally, the endoscopic imaging system pulses the excitation wavelength of electromagnetic radiation for the fluorescent reagent that was administered to the patient. In the example, the patient has cancerous cells and the fluorescent reagent has adhered to the cancerous cells. When the endoscopic imaging system pulses the excitation wavelength for the fluorescent reagent, the fluorescent reagent will fluoresce and emit a relaxation wavelength. If the cancerous cells are present in the scene being imaged by the endoscopic imaging system, then the fluorescent reagent will also be present in the scene and will emit its relaxation wavelength after fluorescing due to the emission of the excitation wavelength. The endoscopic imaging system senses the relaxation wavelength of the fluorescent reagent and thereby senses the presence of the fluorescent reagent in the scene. Because the fluorescent reagent is known to adhere to cancerous cells, the presence of the fluorescent reagent further indicates the presence of cancerous cells within the scene. The endoscopic imaging system thereby identifies the location of cancerous cells within the scene. The endoscopic imaging system may further emit a laser scanning pulsing scheme for generating a topology of the scene and calculating dimensions for objects within the scene. The location of the cancerous cells (as identified by the fluorescence imaging data) may be combined with the topology and dimensions information calculated based on the laser scanning data. Therefore, the precise location, size, dimensions, and topology of the cancerous cells may be identified. This information may be provided to a medical practitioner to aid in excising the cancerous cells. Additionally, this information may be provided to a robotic surgical system to enable the surgical system to excise the cancerous cells.

In a further example implementation, a patient is imaged with an endoscopic imaging system to identify quantitative diagnostic information about the patient's tissue pathology. In the example, the patient is suspected or known to suffer from a disease that can be tracked with hyperspectral imaging to observe the progression of the disease in the patient's tissue. The endoscopic imaging system pulses partitions of red, green, and blue wavelengths of light to generate an RGB video stream of the interior of the patient's body. Additionally, the endoscopic imaging system pulses one or more hyperspectral wavelengths of light that permit the system to “see through” some tissues and generate imaging of the tissue that is affected by the disease. The endoscopic imaging system senses the reflected hyperspectral electromagnetic radiation to generate hyperspectral imaging data of the diseased tissue, and thereby identifies the location of the diseased tissue within the patient's body. The endoscopic imaging system may further emit a laser scanning pulsing scheme for generating a topology of the scene and calculating dimensions of objects within the scene. The location of the diseased tissue (as identified by the hyperspectral imaging data) may be combined with the topology and dimensions information that is calculated with the laser scanning data. Therefore, the precise location, size, dimensions, and topology of the diseased tissue can be identified. This information may be provided to a medical practitioner to aid in excising, imaging, or studying the diseased tissue. Additionally, this information may be provided to a robotic surgical system to enable the surgical system to excise the diseased tissue.

FIG. 34 is a schematic diagram of an imaging system 3400 having a single cut filter. The system 3400 includes an endoscope 3406 or other suitable imaging device having a light source 3408 for use in a light deficient environment. The endoscope 3406 includes an image sensor 3404 and a filter 3402 for filtering out unwanted wavelengths of light or other electromagnetic radiation before reaching the image sensor 3404. The light source 3408 transmits light that may illuminate the surface 3412 in a light deficient environment such as a body cavity. The light 3410 is reflected off the surface 3412 and passes through the filter 3402 before hitting the image sensor 3404.

The filter 3402 may be used in an implementation where a fluorescent reagent or dye has been administered. In such an embodiment, the light source 3408 emits the excitation wavelength for fluorescing the fluorescent reagent or dye. Commonly, the relaxation wavelength emitted by the fluorescent reagent or dye will be of a different wavelength than the excitation wavelength. The filter 3402 may be selected to filter out the excitation wavelength and permit only the relaxation wavelength to pass through the filter and be sensed by the image sensor 3404.

In one embodiment, the filter 3402 is configured to filter out an excitation wavelength of electromagnetic radiation that causes a reagent or dye to fluoresce such that only the expected relaxation wavelength of the fluoresced reagent or dye is permitted to pass through the filter 3402 and reach the image sensor 3404. In an embodiment, the filter 3402 filters out at least a fluorescent reagent excitation wavelength between 770 nm and 790 nm. In an embodiment, the filter 3402 filters out at least a fluorescent reagent excitation wavelength between 795 nm and 815 nm. In an embodiment, the filter 3402 filters out at least a fluorescent reagent excitation wavelength between 770 nm and 790 nm and between 795 nm and 815 nm. In these embodiments, the filter 3402 filters out the excitation wavelength of the reagent and permits only the relaxation wavelength of the fluoresced reagent to be read by the image sensor 3404. The image sensor 3404 may be a wavelength-agnostic image sensor and the filter 3402 may be configured to permit the image sensor 3404 to only receive the relaxation wavelength of the fluoresced reagent and not receive the emitted excitation wavelength for the reagent. The data determined by the image sensor 3404 may then indicate a presence of a critical body structure, tissue, biological process, or chemical process as determined by a location of the reagent or dye.

The filter 3402 may further be used in an implementation where a fluorescent reagent or dye has not been administered. The filter 3402 may be selected to permit wavelengths corresponding to a desired spectral response to pass through and be read by the image sensor 3404. The image sensor 3404 may be a monochromatic image sensor such that pixels of the captured image that exceed a threshold or fall below a threshold may be characterized as corresponding to a certain spectral response or fluorescence emission. The spectral response or fluorescence emission, as determined by the pixels captured by the image sensor 3404, may indicate the presence of a certain body tissue or structure, a certain condition, a certain chemical process, and so forth.

FIG. 35 is a schematic diagram of an imaging system 3500 having multiple cut filters. The system 3500 includes an endoscope 3506 or other suitable imaging device having a light source 3508 for use in a light deficient environment. The endoscope 3506 includes an image sensor 3504 and two filters 3502 a, 3502 b. It should be appreciated that in alternative embodiments, the system 3500 may include any number of filters, and the number of filters and the type of filters may be selected for a certain purpose e.g., for gathering imaging information of a particular body tissue, body condition, chemical process, and so forth. The filters 3502 a, 3502 b are configured for preventing unwanted wavelengths of light or other electromagnetic radiation from being sensed by the image sensor 3504. The filters 3502 a, 3502 b may be configured to filter out unwanted wavelengths from white light or other electromagnetic radiation that may be emitted by the light source 3508.

Further to the disclosure with respect to FIG. 34, the filters 3502 a, 3502 b may be used in an implementation where a fluorescent reagent or dye has been administered. The filters 3502 a, 3502 b may be configured for blocking an emitted excitation wavelength for the reagent or dye and permitting the image sensor 3504 to only read the relaxation wavelength of the reagent or dye. Further, the filters 3502 a, 3502 b may be used in an implementation where a fluorescent reagent or dye has not been administered. In such an implementation, the filters 3502 a, 3502 b may be selected to permit wavelengths corresponding to a desired spectral response to pass through and be read by the image sensor 3504.

The multiple filters 3502 a, 3502 b may each be configured for filtering out a different range of wavelengths of the electromagnetic spectrum. For example, one filter may be configured for filtering out wavelengths longer than a desired wavelength range and the additional filter may be configured for filtering out wavelengths shorter than the desired wavelength range. The combination of the two or more filters may result in only a certain wavelength or band of wavelengths being read by the image sensor 3504.

In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 513 nm and 545 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 565 nm and 585 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 900 nm and 1000 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 425 nm and 475 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 520 nm and 545 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 625 nm and 645 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 760 nm and 795 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 795 nm and 815 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 370 nm and 420 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are customized such that electromagnetic radiation between 600 nm and 670 nm contacts the image sensor 3504. In an embodiment, the filters 3502 a, 3502 b are configured for permitting only a certain fluorescence relaxation emission to pass through the filters 3502 a, 3502 b and contact the image sensor 3504.

In an embodiment, the system 3500 includes multiple image sensors 3504 and may particularly include two image sensors for use in generating a three-dimensional image. The image sensor(s) 3504 may be color/wavelength agnostic and configured for reading any wavelength of electromagnetic radiation that is reflected off the surface 3512. In an embodiment, the image sensors 3504 are each color dependent or wavelength dependent and configured for reading electromagnetic radiation of a particular wavelength that is reflected off the surface 3512 and back to the image sensors 3504. Alternatively, the image sensor 3504 may include a single image sensor with a plurality of different pixel sensors configured for reading different wavelengths or colors of light, such as a Bayer filter color filter array. Alternatively, the image sensor 3504 may include one or more color agnostic image sensors that may be configured for reading different wavelengths of electromagnetic radiation according to a pulsing schedule such as those illustrated in FIGS. 5-7E and 15-16, for example.

FIGS. 36A and 36B illustrate a perspective view and a side view, respectively, of an implementation of a monolithic sensor 3600 having a plurality of pixel arrays for producing a three-dimensional image in accordance with the teachings and principles of the disclosure. Such an implementation may be desirable for three-dimensional image capture, wherein the two-pixel arrays 3602 and 3604 may be offset during use. In another implementation, a first pixel array 3602 and a second pixel array 3604 may be dedicated to receiving a predetermined range of wave lengths of electromagnetic radiation, wherein the first pixel array is dedicated to a different range of wavelength electromagnetic radiation than the second pixel array.

FIGS. 37A and 37B illustrate a perspective view and a side view, respectively, of an implementation of an imaging sensor 3700 built on a plurality of substrates. As illustrated, a plurality of pixel columns 3704 forming the pixel array are located on the first substrate 3702 and a plurality of circuit columns 3708 are located on a second substrate 3706. Also illustrated in the figure are the electrical connection and communication between one column of pixels to its associated or corresponding column of circuitry. In one implementation, an image sensor, which might otherwise be manufactured with its pixel array and supporting circuitry on a single, monolithic substrate/chip, may have the pixel array separated from all or a majority of the supporting circuitry. The disclosure may use at least two substrates/chips, which will be stacked together using three-dimensional stacking technology. The first 3702 of the two substrates/chips may be processed using an image CMOS process. The first substrate/chip 3702 may be comprised either of a pixel array exclusively or a pixel array surrounded by limited circuitry. The second or subsequent substrate/chip 3706 may be processed using any process and does not have to be from an image CMOS process. The second substrate/chip 3706 may be, but is not limited to, a highly dense digital process to integrate a variety and number of functions in a very limited space or area on the substrate/chip, or a mixed-mode or analog process to integrate for example precise analog functions, or a RF process to implement wireless capability, or MEMS (Micro-Electro-Mechanical Systems) to integrate MEMS devices. The image CMOS substrate/chip 3702 may be stacked with the second or subsequent substrate/chip 3706 using any three-dimensional technique. The second substrate/chip 3706 may support most, or a majority, of the circuitry that would have otherwise been implemented in the first image CMOS chip 3702 (if implemented on a monolithic substrate/chip) as peripheral circuits and therefore have increased the overall system area while keeping the pixel array size constant and optimized to the fullest extent possible. The electrical connection between the two substrates/chips may be done through interconnects, which may be wire bonds, bump and/or TSV (Through Silicon Via).

FIGS. 38A and 38B illustrate a perspective view and a side view, respectively, of an implementation of an imaging sensor 3800 having a plurality of pixel arrays for producing a three-dimensional image. The three-dimensional image sensor may be built on a plurality of substrates and may comprise the plurality of pixel arrays and other associated circuitry, wherein a plurality of pixel columns 3804 a forming the first pixel array and a plurality of pixel columns 3804 b forming a second pixel array are located on respective substrates 3802 a and 3802 b, respectively, and a plurality of circuit columns 3808 a and 3808 b are located on a separate substrate 3806. Also illustrated are the electrical connections and communications between columns of pixels to associated or corresponding column of circuitry.

The plurality of pixel arrays may sense information simultaneously and the information from the plurality of pixel arrays may be combined to generate a three-dimensional image. In an embodiment, an endoscopic imaging system includes two or more pixel arrays that can be deployed to generate three-dimensional imaging. The endoscopic imaging system may include an emitter for emitting pulses of electromagnetic radiation during a blanking period of the pixel arrays. The pixel arrays may be synced such that the optical black pixels are read (i.e., the blanking period occurs) at the same time for the two or more pixel arrays. The emitter may emit pulses of electromagnetic radiation for charging each of the two or more pixel arrays. The two or more pixel arrays may read their respective charged pixels at the same time such that the readout periods for the two or more pixel arrays occur at the same time or at approximately the same time. In an embodiment, the endoscopic imaging system includes multiple emitters that are each individual synced with one or more pixel arrays of a plurality of pixel arrays. Information from a plurality of pixel arrays may be combined to generate three-dimensional image frames and video streams.

It will be appreciated that the teachings and principles of the disclosure may be used in a reusable device platform, a limited use device platform, a re-posable use device platform, or a single use/disposable device platform without departing from the scope of the disclosure. It will be appreciated that in a re-usable device platform an end-user is responsible for cleaning and sterilization of the device. In a limited use device platform, the device can be used for some specified amount of times before becoming inoperable. Typical new device is delivered sterile with additional uses requiring the end-user to clean and sterilize before additional uses. In a re-posable use device platform, a third-party may reprocess the device (e.g., cleans, packages and sterilizes) a single-use device for additional uses at a lower cost than a new unit. In a single use/disposable device platform a device is provided sterile to the operating room and used only once before being disposed of.

EXAMPLES

The following examples pertain to preferred features of further embodiments:

Example 1 is a system for imaging in a light deficient environment. The system includes an emitter for emitting pulses of electromagnetic radiation. The system includes an image sensor comprising a pixel array for sensing reflected electromagnetic radiation, wherein the pixel array comprises active pixels and optical black pixels. The system includes a black clamp providing offset control for data generated by the pixel array. The system includes a controller comprising a processor in electrical communication with the image sensor and the emitter. The system is such that at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises one or more of: electromagnetic radiation having a wavelength from about 770 nm to about 790 nm; or electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.

Example 2 is a system as in Example 1, wherein the active pixels are located in a central portion of the pixel array and each of the optical black pixels is positioned at a first side of the active pixels or a second side of the active pixels, wherein the first side and the second side are opposite one another with respect to the central portion.

Example 3 is a system as in any of Examples 1-2, further comprising image signal processing circuitry located remotely with respect to the image sensor.

Example 4 is a system as in any of Examples 1-3, further comprising a long registry comprising one or more of: control parameters for controlling exposure times for the pixel array; control parameters for controlling incremental offset adjustments for the pixel array; or control parameters for controller gains of the pixel array.

Example 5 is a system as in any of Examples 1-4, wherein the long registry further comprises control parameters for controlling operation of the pixel array by adjusting one or more of: analog current for the image sensor, voltage for the image sensor, pixel timing, vertical timing for reading pixels in the pixel array, reset of the image sensor, or initialization of the image sensor.

Example 6 is a system as in any of Examples 1-5, wherein the pixel array comprises columns of optical black pixels and the image sensor is configured to read the columns of optical black pixels a plurality of times during a single blanking period such that a total number of optical black columns in the pixel array is reduced.

Example 7 is a system as in any of Examples 1-6, further comprising a digital to analog converter and a charge pump, and wherein the black clamp is configured to sense a voltage generated by one or more of the digital to analog converter or the charge pump.

Example 8 is a system as in any of Examples 1-7, wherein at least one of the electromagnetic radiation having a wavelength from about 770 nm to about 790 nm and the electromagnetic radiation having a wavelength from about 795 nm to about 815 nm is an excitation wavelength that causes one or more reagents to fluoresce at a wavelength that is different from the excitation wavelength.

Example 9 is a system as in any of Examples 1-8, wherein the image sensor is configured to generate a plurality of exposure frames, wherein each of the plurality of exposure frames corresponds to a pulse of electromagnetic radiation emitted by the emitter and produces a dataset corresponding in time with each pulse of electromagnetic radiation to generate a plurality of datasets corresponding to the plurality of exposure frames.

Example 10 is a system as in any of Examples 1-9, wherein the image sensor is configured to sense each of the plurality of exposure frames during a readout period of the pixel array, wherein the readout period is a duration of time when active pixels in the pixel array are read, and wherein a portion of the blanking period overlaps a portion of the next succeeding readout period.

Example 11 is a system as in any of Examples 1-10, wherein the plurality of exposure frames are combined to form an image frame.

Example 12 is a system as in any of Examples 1-11, wherein at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises a green partition of electromagnetic radiation, a red partition of electromagnetic radiation, and a blue partition of electromagnetic radiation.

Example 13 is a system as in any of Examples 1-12, wherein the emitter is configured to emit, during a pulse duration, a plurality of sub-pulses of electromagnetic radiation having a sub-duration shorter than the pulse duration.

Example 14 is a system as in any of Examples 1-13, wherein one or more of the pulses of electromagnetic radiation emitted by the emitter comprise electromagnetic radiation emitted at two or more wavelengths simultaneously as a single pulse or a single sub-pulse.

Example 15 is a system as in any of Examples 1-14, wherein at least one pulse of the pulses of electromagnetic radiation emitted by the emitter results in an exposure frame created by the image sensor, wherein the system further comprises a display for displaying two or more exposure frames as an image frame.

Example 16 is a system as in any of Examples 1-15, wherein at least a portion of the pulses of electromagnetic radiation emitted by the emitter is an excitation wavelength for fluorescing a reagent, and wherein pulsing the excitation wavelength results in the image sensor generating a fluorescence exposure frame indicating a location of the reagent within a scene.

Example 17 is a system as in any of Examples 1-16, wherein the controller is configured to provide the fluorescence exposure frame to a corresponding system that determines a location of a critical tissue structure based on the fluorescence exposure frame.

Example 18 is a system as in any of Examples 1-17, wherein the controller is further configured to: receive the location of the critical tissue structure from the corresponding system; generate an overlay frame comprising the location of the critical tissue structure; and combine the overlay frame with a color image frame depicting the scene to indicate the location of the critical tissue structure within the scene.

Example 19 is a system as in any of Examples 1-18, wherein the controller is configured to synchronize timing of the pulses of electromagnetic radiation during a blanking period of the image sensor, wherein the blanking period corresponds to a time between a readout of a last row of active pixels in the pixel array and a beginning of a next subsequent readout of active pixels in the pixel array.

Example 20 is a system as in any of Examples 1-19, wherein the controller is configured to adjust a sequence of the pulses of electromagnetic radiation emitted by the emitter based on a threshold, wherein the threshold determines proper illumination of a scene in a light deficient environment.

Example 21 is a system as in any of Examples 1-20, wherein two or more pulses of electromagnetic radiation emitted by the emitter result in two or more instances of reflected electromagnetic radiation that are sensed by the pixel array to generate two or more exposure frames that are combined to form an image frame.

Example 22 is a system as in any of Examples 1-21, wherein at least a portion of the pulses of electromagnetic radiation emitted by the emitter is an excitation wavelength for fluorescing a reagent, and wherein at least a portion of the reflected electromagnetic radiation sensed by the image sensor is a relaxation wavelength of the reagent.

Example 23 is a system as in any of Examples 1-22, wherein the image sensor is configured to sense the relaxation wavelength of the reagent to generate a fluorescence exposure frame, and wherein the controller is configured to provide the fluorescence exposure frame to a corresponding system that identifies one or more critical structures in a body based on the fluorescence exposure frame.

Example 24 is a system as in any of Examples 1-23, wherein the one or more critical structures in the body comprise one or more of a nerve, a ureter, a blood vessel, an artery, a blood flow, cancerous tissue, or a tumor.

Example 25 is a system as in any of Examples 1-24, further comprising a first filter that filters electromagnetic radiation having a wavelength from about 770 nm to about 790 nm.

Example 26 is a system as in any of Examples 1-25, further comprising a second filter that filters electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.

Example 27 is a system as in any of Examples 1-26, further comprising a first filter that filters electromagnetic radiation having a wavelength from about 770 nm to about 790 nm and a second filter that filters electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.

Example 28 is a system as in any of Examples 1-27, further comprising one or more filters that allow electromagnetic radiation having a wavelength from about 790 nm to about 800 nm and above 815 nm to pass through the one or more filters to the image sensor.

Example 29 is a system as in any of Examples 1-28, further comprising a polarization filter located in a path of the pulses of electromagnetic radiation emitted by the emitter.

Example 30 is a system as in any of Examples 1-29, wherein the image sensor comprises a first image sensor and a second image sensor such that the image sensor can generate a three-dimensional image.

Example 31 is a system as in any of Examples 1-30, wherein the emitter is configured to emit a sequence of pulses of electromagnetic radiation repeatedly sufficient for generating a video stream comprising a plurality of image frames, wherein each image frame in the video stream comprises data from a plurality of exposure frames wherein each of the exposure frames corresponds to a pulse of electromagnetic radiation.

Example 32 is a system as in any of Examples 1-31, wherein the pulses of electromagnetic radiation are emitted in a pattern of varying wavelengths of electromagnetic radiation, and wherein the emitter repeats the pattern of varying wavelengths of electromagnetic radiation.

It will be appreciated that various features disclosed herein provide significant advantages and advancements in the art. The following claims are exemplary of some of those features.

In the foregoing Detailed Description of the Disclosure, various features of the disclosure are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, inventive aspects lie in less than all features of a single foregoing disclosed embodiment.

It is to be understood that any features of the above-described arrangements, examples, and embodiments may be combined in a single embodiment comprising a combination of features taken from any of the disclosed arrangements, examples, and embodiments.

It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the disclosure. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the disclosure and the appended claims are intended to cover such modifications and arrangements.

Thus, while the disclosure has been shown in the drawings and described above with particularity and detail, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.

Further, where appropriate, functions described herein can be performed in one or more of: hardware, software, firmware, digital components, or analog components. For example, one or more application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) can be programmed to carry out one or more of the systems and procedures described herein. Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name, but not function.

The foregoing description has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Further, it should be noted that any or all the aforementioned alternate implementations may be used in any combination desired to form additional hybrid implementations of the disclosure.

Further, although specific implementations of the disclosure have been described and illustrated, the disclosure is not to be limited to the specific forms or arrangements of parts so described and illustrated. The scope of the disclosure is to be defined by the claims appended hereto, any future claims submitted here and in different applications, and their equivalents. 

What is claimed is:
 1. A system for endoscopic visualization, the system comprising: an emitter that emits a plurality of pulses of electromagnetic radiation, wherein the emitter comprises a plurality of electromagnetic sources that are selectively activated, and wherein the plurality of electromagnetic sources comprises: a visible source that pulses a visible wavelength of electromagnetic radiation; a first fluorescence source that pulses a first fluorescence excitation wavelength of electromagnetic radiation; and a second fluorescence source that pulses a second fluorescence excitation wavelength of electromagnetic radiation; wherein the first fluorescence excitation wavelength is different from the second fluorescence excitation wavelength; an image sensor comprising a pixel array that senses reflected electromagnetic radiation to generate a plurality of frames; a black clamp for restricting output voltage of one or more pixels of the pixel array; and a controller comprising a processor in electrical communication with the image sensor and the emitter; wherein at least a portion of the plurality of frames sensed by the image sensor comprises a fluorescence frame sensed in response to an emission by the first fluorescence source or the second fluorescence source.
 2. The system of claim 1, wherein the pixel array comprises active pixels and optical black pixels, and wherein the active pixels are located in a central portion of the pixel array and each of the optical black pixels is positioned at a first side of the active pixels or a second side of the active pixels, and wherein the first side and the second side are opposite one another with respect to the central portion.
 3. The system of claim 1, further comprising image signal processing circuitry located remotely with respect to the image sensor, wherein the image signal processing circuitry reduces fixed pattern noise and/or cancels column fixed pattern noise in the plurality of exposure frames based on data output by the black clamp.
 4. The system of claim 1, further comprising a processor long registry for controlling operations of the image sensor, wherein the processor long registry comprises one or more of: control parameters for controlling exposure times for the pixel array; control parameters for controlling incremental offset adjustments for the pixel array; or control parameters for controller gains of the pixel array.
 5. The system of claim 4, wherein the processor long registry further comprises control parameters for controlling operation of the pixel array by adjusting one or more of: analog current for the image sensor, voltage for the image sensor, pixel timing, vertical timing for reading pixels in the pixel array, reset of the image sensor, or initialization of the image sensor.
 6. The system of claim 1, wherein the pixel array comprises columns of optical black pixels and the image sensor is configured to read the columns of optical black pixels a plurality of times during a single blanking period such that a total number of optical black columns in the pixel array is reduced.
 7. The system of claim 1, further comprising a digital to analog converter and a charge pump, and wherein the black clamp is configured to sense a voltage generated by one or more of the digital to analog converter or the charge pump.
 8. The system of claim 1, wherein: the first fluorescence excitation wavelength comprises electromagnetic radiation within a waveband from about 770 nm to about 810 nm; and the second fluorescence excitation wavelength comprises electromagnetic radiation within a waveband from about 795 nm to about 835 nm.
 9. The system of claim 1, wherein each of the plurality of frames corresponds to a pulse of electromagnetic radiation emitted by the emitter, and wherein the fluorescence frame comprises only fluorescence imaging data, and wherein the pixel array senses the fluorescence frame in response to an emission by one of the first fluorescence source of the second fluorescence source.
 10. The system of claim 9, wherein the pixel array of the image sensor senses reflected electromagnetic radiation to generate the plurality of exposure frames during a readout period of the pixel array, and wherein the readout period is a duration of time when active pixels in the pixel array are read.
 11. The system of claim 1, wherein two or more of the plurality of frames are combined to form an image frame, and wherein at least one image frame comprises data from each of a color frame and the fluorescence frame, and wherein the color frame is sensed by the image sensor in response to the emitter pulsing a visible wavelength of electromagnetic radiation.
 12. The system of claim 1, wherein the controller provides instructions to the emitter to actuate the visible source, the first fluorescence source, and the second fluorescence source independently and at different moments in time.
 13. The system of claim 1, wherein the emitter is configured to emit each of the plurality of pulses of electromagnetic radiation only during readout periods of the image sensor, and wherein the emitter is configured to emit a plurality of sub-pulses of electromagnetic radiation during a single readout period.
 14. The system of claim 1, wherein one or more of the plurality of pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation emitted at two or more wavelengths simultaneously as a single pulse or a single sub-pulse.
 15. The system of claim 1, wherein at least one pulse of the plurality of pulses of electromagnetic radiation emitted by the emitter results in a frame sensed by the image sensor, and wherein the system further comprises a display for displaying two or more frames simultaneously as an image frame.
 16. The system of claim 1, wherein at least one of the first fluorescence excitation wavelength or the second fluorescence excitation wavelength is finely tuned to fluoresce a fluorescence reagent within a scene.
 17. The system of claim 1, wherein the controller is configured to provide the fluorescence frame to a corresponding system that determines a location of a tissue structure based on the fluorescence frame.
 18. The system of claim 17, wherein the controller is further configured to: receive the location of the tissue structure from the corresponding system; generate an overlay frame comprising the location of the tissue structure; and combine the overlay frame with a color image frame depicting the scene to indicate the location of the tissue structure within the scene.
 19. The system of claim 1, wherein the controller is configured to synchronize timing of each of the plurality of pulses of electromagnetic radiation during a blanking period of the image sensor, wherein the blanking period corresponds to a time between a readout of a last row of active pixels in the pixel array and a beginning of a next subsequent readout of active pixels in the pixel array.
 20. The system of claim 1, wherein the controller is configured to adjust a sequence of the plurality of pulses of electromagnetic radiation emitted by the emitter based on a threshold, wherein the threshold determines proper illumination of a scene in a light deficient environment.
 21. The system of claim 1, wherein two or more pulses of electromagnetic radiation emitted by the emitter result in two or more instances of reflected electromagnetic radiation that are sensed by the pixel array to generate two or more exposure frames that are combined to form an image frame.
 22. The system of claim 1, wherein the image sensor senses the fluorescence frame by sensing a relaxation wavelength of a fluorescent reagent, and wherein the fluorescent reagent fluoresces in response to an emission by one of the first fluorescence source or the second fluorescence source.
 23. The system of claim 22, wherein the controller actuates the emitter to pulse a plurality of different partitions of electromagnetic radiation at different times in a pattern sequence, and wherein the pattern sequence comprises an instruction to pulse only one of the first fluorescence excitation wavelength or the second fluorescence excitation wavelength at one time such that the pixel data for the fluorescence frame comprises only fluorescence imaging data for identifying a location of the fluorescent reagent within a scene.
 24. The system of claim 23, wherein the tissue structure comprises one or more of a nerve, a ureter, a blood vessel, an artery, a blood flow, cancerous tissue, or a tumor.
 25. The system of claim 1, further comprising a first filter that filters electromagnetic radiation having a wavelength from about 770 nm to about 810 nm.
 26. The system of claim 1, further comprising a second filter that filters electromagnetic radiation having a wavelength from about 775 nm to about 815 nm.
 27. The system of claim 1, further comprising a first filter that filters electromagnetic radiation having a wavelength from about 770 nm to about 810 nm and a second filter that filters electromagnetic radiation having a wavelength from about 775 nm to about 815 nm.
 28. The system of claim 1, further comprising one or more filters that allow electromagnetic radiation having a wavelength from about 775 to about 815 nm to pass through the one or more filters to the image sensor.
 29. The system of claim 1, further comprising a polarization filter located in a path of the plurality of pulses of electromagnetic radiation emitted by the emitter.
 30. The system of claim 1, wherein the image sensor comprises a first image sensor and a second image sensor such that the image sensor can generate a three-dimensional image.
 31. The system of claim 1, wherein the emitter is configured to emit a sequence of pulses of electromagnetic radiation repeatedly sufficient for generating a video stream comprising a plurality of image frames, and wherein each image frame in the video stream comprises data from two or more of the plurality of exposure frames, and wherein each of the plurality of exposure frames corresponds to a pulse of electromagnetic radiation.
 32. The system of claim 1, wherein the plurality of pulses of electromagnetic radiation are emitted in a pattern of varying wavelengths of electromagnetic radiation, and wherein the emitter repeats the pattern of varying wavelengths of electromagnetic radiation. 